Mathematics Chapter 1 Real Numbers
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    NCERT Solution For Class 10 Mathematics

    Real Numbers Here is the CBSE Mathematics Chapter 1 for Class 10 students. Summary and detailed explanation of the lesson, including the definitions of difficult words. All of the exercises and questions and answers from the lesson's back end have been completed. NCERT Solutions for Class 10 Mathematics Real Numbers Chapter 1 NCERT Solutions for Class 10 Mathematics Real Numbers Chapter 1 The following is a summary in Hindi and English for the academic year 2021-2022. You can save these solutions to your computer or use the Class 10 Mathematics.

    Question 1
    CBSEENMA10006078

    Use Euclid’s division algorithm to find the HCF of:

    (i)135 and 225 (ii) 196 and 38220.

    Solution
    (i) Given integers are 135 and 225, clearly 225 > 135. Therefore, by applying Euclid’s division lemma to 225 and 135, we get

    If. Since, the remaindei 90 ≠ 0, we apply division lemma to 135 and 90, to ge.

    We consider the new divisor 90 and new remainder 45 and apply division lemma to get

    The remainder of this step is zero. So, the divisor at this stage or the remainder at the previous stage i.e., 45 is the HCF of 135 and 225.
    (ii) Given integers are 196 and 38220. Therefore by applying Euclid’s division lemma to 196 and 38220, we get


    The remainder at this step is zero. So. our procedures stops and divisor at this stage i.e. 196 is the HCF of 196 and 38220.

    Question 2
    CBSEENMA10006079

    Show that any positive odd integer is of the form 6q + 1, or 6q + 3, or 6q + 5, where q is some integer.

    Solution

    Let a be any odd positive integer and b = 6. Let q be a quotient and r be remainder.

    Therefore, applying division lemma, we have 

    Question 3
    CBSEENMA10006081

    An army contingent of 616 members is to march behind an army band of 32 members in a parade. The two groups are to march in the same number of columns. What is the maximum number of columns in which they can march?

    Solution

    Given integers are 32 and 616.

    Clearly 616 > 32. Therefore, applying Euclid’s division lemma to 616 and 32, we get

    Since, the remainder 8 ≠ 0, we apply the division lemma, to get

    The remainder has now become zero, so our procedure stops. Since the divisor at this stage is 8.

    Therefore, the maximum number of columns in which both 616 members (army contingent) and 32 members (army band) can march is 8.

     

    Question 4
    CBSEENMA10006082

    Use Euclid’s division lemma to show that the square of any positive integer is either of the form 3m or 3m + 1 for some integer m.

    Solution

    Let a be any positive integer. Let q be the quotient and r be remainder. Then a = bq + r where q and r are also positive integers and 0 ≤ r < b

    Taking b = 3, we get

    a = 3q + r; where 0 ≤ r < 3

    When, r = 0 = ⇒ a = 3q

    When, r = 1 = ⇒ a = 3q + 1

    When, r = 2 = ⇒ a = 3q + 2

    Now, we have to show that the squares of positive integers 3q, 3q + 1 and 3q + 2 can be expressed as 3m or 3m + 1 for some integer m.

    ⇒ Squares of 3q = (3q)2

    = 9q2 = 3(3q)2 = 3 m where m is some integer.

    Square of 3q + 1 = (3q + 1)2

    = 9q2 + 6q + 1 = 3(3q2 + 2 q) + 1

    = 3m +1, where m is some integer

    Square of 3q + 2 = (3q + 2)2

    = (3q + 2)2

    = 9q2 + 12q + 4

    = 9q2 + 12q + 3 + 1

    = 3(3q2 + 4q + 1)+ 1

    = 3m + 1 for some integer m.

    ∴ The square of any positive integer is either of the form 3m or 3m + 1 for some integer m.

    Question 5
    CBSEENMA10006083

    Use Euclid’s division lemma to show that the cube of any positive integer is of the form 9m, 9m + 1 or 9m + 8.

    Solution

    Let a and b be two positive integergs such that a is greater than b; then :

    a = bq + r;

    where q and r are positive integers 0 ≤ r < b.

    Taking b = 3, we get

    a = 3q + r ; where 0 ≤ r < 3.

    ⇒ Different values of integer a are 3q, 3q + 1 or 3q + 2.

    Cube of 3q = (3q)3

    = 27q3 = 9(3q3) = 9m ;

    where m is some integer.

    Cube of 3q + 1 = (3q + 1)3

    = (3q + 3(3q)2 × 1 + 3(3q) × 12+ l3

    [∵ (a + b)3 = a3 + 3a2b + 3ab2 + 1]

    = 27q3 + 27q2 + 9q + 1

    = 9(3q3 + 3q2 + q) + 1

    = 9m + 1; where m is some integer.

    Cube of 3q + 2 = (3q + 2)3

    = (3q)3 + 3(3q)2 × 2 + 3 × 3q × 22 + 23

    = 27q3 + 54q2 + 36q + 8

    = 9(3q3 + 6q2 + 4q) + 8 = 9m + 8; where m is some integer.

    ∴ Cube of any positive integer is of the form 9m or 9m + 1 or 9m + 8.

    Question 6
    CBSEENMA10006085

    Express each number as a product of its prime factors: (i) 140 

    Solution

    (i) 140 

    So,    140 = 2 × 2 × 5 × 7

    = 22 × 5 × 7.

    Question 7
    CBSEENMA10006086

    Express each number as a product of its prime factors: (ii) 156 

    Solution

    (ii) 156

    So,    156 = 2 × 2 × 3 × 13

    = 22 × 3 × 13

    Question 8
    CBSEENMA10006088

    Express each number as a product of its prime factors: (ii) 156 (iii) 3825 (iv) 5005 (v) 7429

    Solution

    (iii) 3825

    So, 3825 = 3 × 3 × × 5 × 5 × 17

    = 32 × 52 × 17.

    Question 9
    CBSEENMA10006089
    Question 10
    CBSEENMA10006090

    Express each number as a product of its prime factors:  (v) 7429

    Solution

    (v) 7429

    So, 7429 = 17 × 19 × 23.

    Question 11
    CBSEENMA10006092

    Find the LCM and HCF of the following pairs of integers and verify that LCM × HCF = product of the two numbers. (i) 26 and 91

    Solution
    (i) 26 and 91

    So,    26 = 2 × 13

    and    91 = 7 × 13

    ∴ H.C.F. (26, 91) = 13

    and L.C.M. (26, 91) = 2 × 7 × 13 = 182

    Verification :

    L.C.M. × H.C.F. = 182 × 13 = 2366

    Product of the two nos. = 26 × 91 = 2366

    ∴ L.C.M. × H.C.F. = Product of the two nos.

    Verified.



    Question 12
    CBSEENMA10006094

    Find the LCM and HCF of the following pairs of integers and verify that LCM × HCF = product of the two numbers.  (ii) 510 and 92 

    Solution

    (ii)
     

    So,    510 = 2 × 3 × 5 × 17

    and    92 = 2 × 2 × 23

    ∴ H.C.F. (510, 92) = 2

    and L.C.M. (510, 92) = 2 × 2 × 3 × 5 × 17 × 23

    = 23460

    Verification :

    L.C.M. × H.C.F. = 23460 × 2 = 46920

    Product of the two nos. = 510 × 92 = 46920

    L.C.M. × H.C.F. = Product of the two nos.

    Verified.

    Question 13
    CBSEENMA10006095

    Find the LCM and HCF of the following pairs of integers and verify that LCM × HCF = product of the two numbers.  (iii) 336 and 54

    Solution

    (iii)

    So, 336 = 24 × 3 × 7

    and    54 = 2 × 33

    ∴ H.C.F. = 2 × 3 = 6

    L.C.M. = 24 × 33 × 7 = 3024

    = 23460

    Verification :

    L.C.M. × H.C.F. = 3024 × 6 = 18144

    Product of the two nos. = 336 × 54 = 18144

    L.C.M. × H.C.F. = Product of the two nos.

    Verified.

    Question 14
    CBSEENMA10006097

    Find the LCM and HCF of the following integers by applying the prime factorisation method. (i) 12, 15 and 21 

    Solution

    (i) 12, 15 and 21 

    Now,    12 = 2 × 2 × 3= 22 × 3,

    15 = 3 × 5, 21 = 3 × 7

    Here, 3 is the smallest common prime factor.

    ∴ H.C.F. (12, 15, 21) = 3

    And 22, 31, 51 and 71 are the greatest powers of prime factors.

    ∴ L.C.M. (12, 15,21)= 22 × 31 × 51 × 71 =420.

    Question 15
    CBSEENMA10006098

    Find the LCM and HCF of the following integers by applying the prime factorisation method. (ii) 17, 23 and 29 

    Solution

    (ii) 17, 23 and 29 

    Now, 17 = 1 × 17, 23 = 1 × 23, 29 = 1 × 29

    Here, 1 is the smallest common factor.

    ∴ H.C.F. (17, 23, 29)= 1

    And 171, 231 and 291 are the greatest powers of prime factors.

    ∴ L.C.M. (17, 23, 29) = 17 × 23 × 29 = 11339.


    Question 16
    CBSEENMA10006100

    Find the LCM and HCF of the following integers by applying the prime factorisation method. (iii) 8, 9 and 25

    Solution

    (iii) 8, 9 and 25

    Now,    8 = 2 × 2 × 2 = 23,

    9 = 3 × 3 = 32

    and    25 = 5 × 5 = 52

    Since, there is no smallest common factor.

    ∴ H.C.F. (8, 9, 25) = 1.

    And 23, 32, and 52 are greatest powers of prime factors.

    ∴ L.C.M. (8, 9, 25) = 23 × 32 × 52 = 1800.

    Question 17
    CBSEENMA10006102

    Given that HCF (306, 657) = 9, find LCM (306, 657).

    Solution
    HCF (306, 657) = 9
    LCM (306, 657)  = fraction numerator 306 cross times 657 over denominator 9 end fraction
                           equals 201042 over 9
equals 22338

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    Question 18
    CBSEENMA10006103

    Check whether 6n can end with the digit 0 for any natural number n

    Solution

    If the number 6n, for any natural number n, ends with digit 0, then it is divisible by 5. That is, the prime factorisation of 6n contains the prime 5. This is not possible because the primes in the factorisation of 6n are 2 and 3 and the uniqueness of the Fundamental Theorem of Arithmetic guarantees that there are no other primes in the factorisation of 6n.

    So, there is no natural number n for which 6n ends with digit zero.

    Question 19
    CBSEENMA10006104

    Explain why 7 × 11 × 13 + 13 and 7 × 6 × 5 × 4 × 3 × 2 × 1 + 5 are composite numbers.

    Solution

    Any positive number, which has more than two factors, is called a composite number.

    Since,

    7 × 11 × 13 + 13 = 13 × (7 × 11 + 1)

    = 13 × 78

    = 13 × 13 × 3 × 2

    that is, the given number has more than two factors and it is a composite number.

    Similarly,

    7 × 6 × 5 × 4 × 3 + 5

    = 5 × (7 × 6 × 4 × 3 + 1)

    = 5 × 505

    = 5 × 5 × 101

    ⇒ The given number is a composite number.

    Question 20
    CBSEENMA10006106

    There is a circular path around a sports field. Sonia takes 18 minutes to drive one round of the field, while Ravi takes 12 minutes for the same. Suppose they both start at the same point and at the same time, and go in the same direction. After how many minutes will they meet again at the starting point?

    Solution

    Required number of minutes is the LCM of 18 and 12.

    We have,

    18 = 2 × 32

    and    12 = 22 × 3

    ∴ LCM of 18 and 12 is 22 × 32 = 36.

    Hence, Ravi and Sonia will meet again at the starting point after 36 minutes.

    Question 21
    CBSEENMA10006108

    Prove that square root of 5 is irrational.

    Solution
    Let us assume, to the contrary, that <pre>uncaught exception: <b>mkdir(): Permission denied (errno: 2) in /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php at line #56mkdir(): Permission denied</b><br /><br />in file: /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php line 56<br />#0 [internal function]: _hx_error_handler(2, 'mkdir(): Permis...', '/home/config_ad...', 56, Array)
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#6 {main}</pre> is rational.
    So, we can find coprime integers a and b (≠ 0) such that
                     space space space space space space space space space space space space square root of 5 equals straight a over straight b space
space space space rightwards double arrow space space space space space space square root of 5 space straight b equals straight a

    Squaring on both sides, we get

    5b2 = a2

    Therefore, 5 divides a2

    Therefore, 5 divides a

    So, we can write

    a = 5c for some integer c.

    Substituting for a, we get

    5b2 = 25c2

    ⇒    b2 = 5c2

    This means that 5 divides b2, and so 5 divides b.

    Therefore, a and b have at least 5 ts a common factor.

    But this contradicts the fact that a and b have no common factors other than 1.

    This contradiction has arisen because of our incorrect assumption that square root of 5 is rational.

    So, we conclude that square root of 5 is irrational.

    Question 22
    CBSEENMA10006112

    Prove that space 3 plus 2 square root of 5is irrational.

    Solution
    Let us assume, to the contrary that space 3 plus 2 square root of 5 is rational.

    That is, we can find coprime a and b (b ≠ 0)
    such space that space space space space space space space space space space space 3 plus 2 square root of 5 equals straight a over straight b
    Therefore comma space space straight a over straight b space equals space 3 space plus 2 square root of 5 space
    rightwards double arrow space space space space space space fraction numerator straight a minus 3 straight b over denominator straight b end fraction equals 2 square root of 5
rightwards double arrow space space space space space space space space fraction numerator straight a minus 3 straight b over denominator 2 straight b end fraction equals square root of 5 rightwards double arrow fraction numerator straight a over denominator 2 straight b end fraction minus 3 over 2
    Since a and b are integers, we get   fraction numerator a over denominator 2 b end fraction minus 3 over 2 is rational, and so square root of 5 is rational.
    But this contradicts the fact that square root of 5 is irrational.

    This contradiction has arisen because of our incorrect assumption that space space space 3 plus 2 square root of 5 is rational

    So, we conclude that space space 3 plus 2 square root of 5 is irrational.

    Question 23
    CBSEENMA10006115

    Prove that the following are irrational:

    (i)  fraction numerator 1 over denominator square root of 2 end fraction

    Solution

    (i) fraction numerator 1 over denominator square root of 2 end fraction
    Let us assume, to the contrary, that fraction numerator 1 over denominator square root of 2 end fraction is rational.
    So, we can find coprime integers a and b (≠ 0) such that
    rightwards double arrow space space space space space space fraction numerator 1 over denominator square root of 2 end fraction equals straight a over straight b rightwards double arrow square root of 2 equals straight b over straight a
    Since, a and b are integers, straight a over straight b si rational, and so square root of 2 is irrational
    So, we conclude that fraction numerator 1 over denominator square root of 2 end fraction is irrational.

    Question 24
    CBSEENMA10006118

    Prove that the following are irrational:

    (ii)  7 square root of 5

    Solution

    (ii) 7 square root of 5
    Let us assume to the contrary, that 7 square root of 5 is rational.
    So we can find coprime integers a and b (space space not equal to0 ) such that
    italic space italic space italic space italic space italic space italic space italic 7 square root of italic 5 italic equals a over b
italic rightwards double arrow italic space italic space italic space italic space square root of italic 5 italic equals fraction numerator a over denominator italic 7 b end fraction
    Since, a and b are integers,  fraction numerator straight a over denominator 7 straight b end fraction is rational. and so, square root of 5 is rational
    But this contradicts the fact that square root of 5 is irrational.
    Therefore  7 square root of 5 is irrational.

    Question 25
    CBSEENMA10006121

    Prove that the following are irrational:

    (iii)    6 plus square root of 2

    Solution
    Let us assume to the contrary, that square root of 2 is rational.
    Then,    6 plus square root of 2 is rational.
    So, we can find coprime integers a and b (≠ 0) such that
    space space space space space space space space 6 plus square root of 2 equals straight a over straight b
rightwards double arrow space space space space 6 minus straight a over straight b equals square root of 2
    Since, a and b are integers, we get straight a over straight b is rational and so, 6 minus straight a over straight b is rational and so, square root of 2 is rational.
    But this contradicts the fact that square root of 2  is irrational.
    So, we conclude that  6 plus square root of 2 is irrational.
    Question 37
    CBSEENMA10006141

    The following real numbers have decimal expansions as given below. In each case, decide whether they are rational or not. If they are rational, and of the form , p q what can you say about the prime factors of q?

    (i) 43.123456789

    Solution
    left parenthesis straight i right parenthesis space 43.123456789 space space equals 43123456789 over 1000000000
space space space space space space space space space space space space space space space space space space space space space space space space space space equals 43123456789 over 10 to the power of 9
space space space space space space space space space space space space space space space space space space space space space space space space space space space space equals fraction numerator 43123456789 over denominator 2 to the power of 9 cross times 5 to the power of 9 end fraction

    ∴ 43.123456789 is a rational number of the form p/q, where ‘p’ and ‘q’ are co-primes and the prime factors of ‘q’ are of the form 2n.5n, where n is nonnegative integer.
    Question 39
    CBSEENMA10006144

    The following real numbers have decimal expansions as given below. In each case, decide whether they are rational or not. If they are rational, and of the form , p q what can you say about the prime factors of q?

    left parenthesis iii right parenthesis space space 43. top enclose 123456789

    Solution
    ∴ 43.123456789123456789... which is non-terminating and repeating. Therefore, it is a rational number which can be expressed in the form p/q, where p and q are co-primes and the prime factors of ‘q’ are of the form 2n.5n, where ‘n’ is non-negative integer.

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    Question 40
    CBSEENMA10006145

    In a morning walk Nimit, Tanvika and Mehul step off together, their steps measure 84 cm, 90 cm and 120 cm respectively. What is the minimum distance each should walk so that one can cover the distance in complete steps.

    Solution

     Required distance is the LCM of 84 cm, 90 cm and 120 cm.

    Thus,

    Since, 84 = 2 × 2 × 3 × 7 = 22 × 3 × 7

    90 = 2 × 3 × 3 × 5 = 2 × 32 × 5

    and    120 = 2 × 2 × 2 × 3 × 5

    = 23 × 3 × 5

    ∴ LCM = Product of each prime factor with highest power

    = 23 × 32 × 5 × 7 = 2520

    = 25 m 20 cm

    Problems Based on Irrational Numbers

    Question 41
    CBSEENMA10006147

     Find the [HCF m LCM] for the numbers 100 and 190.

    Solution

    ∵ HCF × LCM

    = Product of the numbers

    = 100 × 190

    = 19000 Ans.

    Question 42
    CBSEENMA10006148

     State fundamental theorem of arithmetic. 

    Solution
    Every composite number can be expressed as product of primes and this decomposition is unique, apart from the order in which prime factors occur.
    Question 43
    CBSEENMA10006149

    Write a rational number between <pre>uncaught exception: <b>mkdir(): Permission denied (errno: 2) in /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php at line #56mkdir(): Permission denied</b><br /><br />in file: /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php line 56<br />#0 [internal function]: _hx_error_handler(2, 'mkdir(): Permis...', '/home/config_ad...', 56, Array)
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#6 {main}</pre>.

    Solution

    A rational number between <pre>uncaught exception: <b>mkdir(): Permission denied (errno: 2) in /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php at line #56mkdir(): Permission denied</b><br /><br />in file: /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php line 56<br />#0 [internal function]: _hx_error_handler(2, 'mkdir(): Permis...', '/home/config_ad...', 56, Array)
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#6 {main}</pre>

    Question 44
    CBSEENMA10006150

    State Euclid’s division algorithm.

    Solution

    Given two positive integers a and b, there exists a unique pair of integers q and r such that

    a = bq + r, 0 ≤ r < b.

    Question 45
    CBSEENMA10006151

    Consider the number 12n, where n is a natural number. Check whether there is any value of n ∊ N for which 12n ends with the digit zero.

    Solution

    We know, if any number ends with the digit zero it is always divisible by 5.

    ⇒ If 12n ends with the digit zero, it must be divisible by 5.

    This is possible only if prime factorisation of 12n contains the prime number 5.

    Now, 12 = 2 × 2 × 3 = 22 × 3

    ⇒ 12n = (22 × 3)n = 22 × 3n

    i.e., prime factorisation of 12' does not contain the prime number 5.

    ⇒ There is no value of n ∊ N for which 12n ends with the digit zero.

    Question 46
    CBSEENMA10006152

    Consider the number 6n, where n is a natural number. Check whether there is any value of n ∊ N for which 6n is divisible by 7.

    Solution

    Since 6 = 2 × 3

    6n = 2n × 3n

    ⇒ The prime factorisation of given number 6n does not contain the prime number 7.

    ⇒ 6n is not divisible by 7.

    Question 47
    CBSEENMA10006153

    Given that L.C.M. of (150, 100) = 300, find H.C.F. (150, 100).

    Solution

    L.C.M. (150, 100) = 300

    ⇒ L.C.M. of 150 and 100 = 300

    And, the product of numbers 150 and 100 = 150 × 100

    Now, H.C.F. (150, 100)
    equals fraction numerator Product space of space 150 space and space 100 over denominator straight L. straight C. straight M. space left parenthesis 150 comma space 100 right parenthesis end fraction
equals fraction numerator 150 cross times 100 over denominator 300 end fraction equals 50

    Question 48
    CBSEENMA10006154

    The H.C.F. and L.C.M. of two numbers are 12 and 240 respectively. If one of these numbers is 48; find the other number.

    Solution

     Since, the product of two numbers

    = Their H.C.F. × their L.C.M

    ⇒ a × b = H.C.F. × L.C.M. [where a and b are two numbers]
    rightwards double arrow  Other No. space space space space space space space space space space equals fraction numerator 12 cross times 240 over denominator 48 end fraction equals 60

    Question 49
    CBSEENMA10006158

    What is the HCF of 52 and 130.

    Solution

    i.e.

    Prime factors of

    52 = 2 × 2 × 13

    and, Prime factors of

    130 = 2 × 5 × 13

    ∴ HCF (52, 130) = 2 × 13 = 26


    Question 50
    CBSEENMA10006162

    Without actual division find whether the rational number  3 over 3750  is a terminating or a non-terminating repeating decimal.

    Solution
    We have.
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#6 {main}</pre>
    Since, denominator (q) is expressed in the form of 2n × 5n, so it is term inacting.
    Question 51
    CBSEENMA10006165
    Question 52
    CBSEENMA10006167

    Write the prime factors of 84.

    Solution

    i.e. 84 = 2 × 2 × 3 × 7 = 22 × 3 × 7
    Question 53
    CBSEENMA10006169

    Write the condition to be satisfied by q so that a rational number p/q has a terminating decimal expansion.

    Solution

    q is of the form of 2m × 5n, where m, n are negative integers.

    Question 55
    CBSEENMA10006174

    Find the HCFF of 960 and 432.

    Solution


    i.e.

    960 = 2 × 2 × 2 × 2 × 2 × 2 × 3 × 5

    = 26 × 3 × 5

    432 = 2 × 2 × 2 × 2 × 3 × 3 × 3

    = 24 × 33

    HCF (960, 432) = 24 × 3

    = 16 × 3

    = 48

    Question 56
    CBSEENMA10006176

    Write the prime factors of 546.

    Solution

    i.e. 546 = 2 × 3 × 7 × 13.
    Question 57
    CBSEENMA10006179

    Write whether the rational number  <pre>uncaught exception: <b>file_put_contents(/home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/plugin/web/../../../../../../formulas/31/61/183836b34a293c5df6820d82a5ac.ini): failed to open stream: Permission denied (errno: 2) in /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/sys/io/File.class.php at line #12file_put_contents(/home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/plugin/web/../../../../../../formulas/31/61/183836b34a293c5df6820d82a5ac.ini): failed to open stream: Permission denied</b><br /><br />in file: /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/sys/io/File.class.php line 12<br />#0 [internal function]: _hx_error_handler(2, 'file_put_conten...', '/home/config_ad...', 12, Array)
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#7 {main}</pre> will have a terminating decimal or a non

    terminating repeating decimal expansion.

    Solution
    51 over 1500 equals 17 over 500 equals fraction numerator 17 over denominator 2 squared straight x 5 cubed end fraction
    Since, denominator in the forms 2m5n. So, it has terminating expansion.
    Question 58
    CBSEENMA10006183

    The HCF and LCM of hvo numbers are 9 and 360 respectively. If one number is 45. Write the other number.

    Solution
    Let another number = x.
    H.C.F. (4, 5) = 9
    L.C.M. (45, x) = 360
    Now   HCF cross times LCM space equals space 45 cross times straight x
rightwards double arrow space 9 cross times 360 equals 45 cross times straight x
rightwards double arrow space space straight x space equals space 360 over 5 equals 72
    Question 59
    CBSEENMA10006184

    What is the exponent of 3 in the prime factorization of 864 ?

    Solution

    864 = 3 × 3 × 3 × 3 × 7

    = 34 × 7
    Hence, exponent of 3 in the prime factorization of 864 is 4.

    Question 60
    CBSEENMA10006185
    Question 61
    CBSEENMA10006186
    Question 62
    CBSEENMA10006187

    Explain why 7 × 11 × 13 + 13 and 7 × 6 × 5 4 × 3 × 2 × 1 + 5 are composite numbers.

    Solution

    Since 7 × 11 ×13 + 13 = (7 ×11 + 1) × 13

    and 7 × 6 × 5 × 4 × 3 × 2 × 1 × 5 = (7 × 6 × 4 × 3 × 2 × 1) × 5

    Question 66
    CBSEENMA10006193
    Question 68
    CBSEENMA10006196
    Question 69
    CBSEENMA10006199
    Question 72
    CBSEENMA10006205
    Question 74
    CBSEENMA10006210

    Find the missing number a, b and c in the following factorisation :


    Solution
    a = 5313, b = 1771 and c = 253 
    Question 77
    CBSEENMA10006217

    Write the decimal expansions of the following rational numbers.

    left parenthesis straight i right parenthesis space 13 over 3125 space space left parenthesis ii right parenthesis space space 17 over 512

    Solution
    (i) 0.00416 (ii) 0.033203125.
    Question 78
    CBSEENMA10006226

    Use Euclid’s division algorithm to find the HFC of 867 and 255

    Solution

    Given integers are 867 and 255.

    Clearly 867 > 255

    Therefore, by applying Euclid’s division lemma to 867 and 255, we get

    II.  Since the remainder 102 ≠ 0, we apply division lemma to get,

    III. We consider the new divisor 102 and new remainder 51 and apply division lemma to get,


    The remainder at this step is zero. So, the divisor at this stage or the remainder at the previous stage i.e., 51 is the HCF of 867 and 255.

    Question 79
    CBSEENMA10006240

    Use Euclid’s algorithm to find the HCF of 4052 and 12576.

    Solution

     Given integers are 4052 and 12576, clearly 12576 > 4052.

    Therefore, by applying Euclid's division lemma to 4052 and 12576, we get

    I. 12576 = 4052 × 3 + 420

    II. Since the remainder 420 ≠ 0, we apply division lemma to 4052 and 420 to get

    III. We consider the new divisor 420 and new remainder 272 and apply division lemma to gel   

    IV. We consider the new divisor 272 and new remainder 148 and apply division lemma to get


    V. We consider the new divisor 148 and new remainder 124 and apply division lemma to get

    VI. We consider the new divisor 124 and new remainder 24 and apply division lemma to get

    VII.We consider the new divisor 24 and new remainder 4 and apply division lemma to get

    The remainder at this step is zero. So, the divisor at this stage or the remainder at the previous stage i.e. 4 is the HCF of 4052 and 12576.

     

    Sponsor Area

    Question 80
    CBSEENMA10006242

    Use Euclid’s division to find HCF of 126 and 1078.

    Solution
    Given integers are 126 and 1078. Clearly 1078 > 126.
    Therefore, by applying Euclid’s division lemma to 126 and 1078, we get


    II. Since, the remainder 70 ≠ 0, we apply division lemma to 70 and 126 to get

    III. We consider the new divisor 70 and new remainder 56 and apply division lemma to get

     

    IV. We consider the new divisor 56 and new remainder 14 and apply division lemma to get
    Question 81
    CBSEENMA10006246

     Find the largest number which divides 245 and 1029 leaving remainder 5 in each case.

    Solution

    It is given that required number which divides 245 and 1029, the remainder is 5 in each case.

    ⇒ 245 - 5 = 240 and 1029 - 5 = 1024 are completely divisible by the required number.

    Since, it is given that the required number is the largest number.

    Therefore, it is the HCF of 240 and 1024.

    Now, finding HCF by Euclid’s division algorithm.

    Given integers are 240 and 1024.

    Clearly 1024 > 240.

    Therefore, it is the HCF of 240 and 1024 and 240, we get

    II. Since, the remainder 64 ≠ 0, we apply division lemma to get

    III. We consider the new divisor 64 and remainder 48 and apply division lemma to get

    IV. We consider the new divisor 48 and new remainder 16 to get

    V. The remainder at this step is zero. So, the divisor at this stage or the remainder at the previous stage i.e., 16 is the HCF of 245 and 1029.

    Question 82
    CBSEENMA10006248

    Find the largest number which divides 615 and 963 leaving remainder 6 in each case.

    Solution

    It is given that required number when divides 615 and 963, the remainder is 6 in each case.

    ⇒ 615 - 6 = 609 and 963 - 6 = 957 are completely divisible by the required number.

    Since, it is given that the required number is the largest number. Given integers are 957 and 609 clearly 957 > 609.

    Therefore, it is the HCF of 609 and 957.

    Now, finding HCF by using Euclid’s division lemma to 609 and 957, we get

    II. Since the remainder 348 ≠ 0, we apply division lemma to 348 and 609 to get

    III. We consider the new divisor 348 and new remainder 261 and apply division lemma to get

    IV. We consider the new divisor 261 and new remainder 87 and apply division lemma to get

    The remainder at this step is zero. So, the divisor at this stage or the remainder at the previous stage i.e., 87 is the HCF of 615 and 963.

    Question 83
    CBSEENMA10006250

    What is the largest number that divides 626, 3127 and 15628 and leaves remainders of 1, 2 and 3 respectively.

    Solution

    Clearly the required number is the HCF of the following numbers

    626 - 1 = 625, 3127 - 2 = 3125 and

    15628 - 3 = 15625

    Case I. Finding the HCF of 625 and 3125 by applying Euclid’s division lemma.

    I. 3125 = 625 × 5 + 0

    Since, the remainder at this stage is zero, so the divisor i.e., 625 at this stage is the HCF of 625 and 3125.
    Case II. Finding the HCF of 625 and third number 15625 by applying Euclid’s division lemma.


    Now, the remainder at this stage is zero. So the divisor i.e., 625 at this stage is the HCF of 625 and 15625.

    Hence, HCF of (626, 3127, 15628) is 625.

    Question 84
    CBSEENMA10006253

    Three sets of Physics, Chemistry and Biology books have to be stacked in such a way that all the books are stored topic-wise and the height of each stack is the same. The number of Physics books is 105, the number of Chemistry books is 140 and the number of Biology books is 175. Assuming that the books are of the same thickness, determine the number of stacks of Physics, Chemistry and Biology books.

    Solution

     In order to arrange the books as required, we have to find the largest number that divides 105, 140 and 175 exactly.

    Clearly, required number is the HCF of 105, 140 and 175.

    Case I :

    I. Finding HCF of 105 and 140 by applying Euclid’s division lemma, we get

    II. Since, the remainder 35 ≠ 0, we apply division lemma to get

    Since, the remainder at this stage is zero, so the divisor i.e., 35 at this stage is the HCF of 105 and 140.

    Case II :

    I. Finding the HCF of 35 and 175 by applying Euclid’s division lemma, we get

    II. Since the remainder at this stage is zero, so the divisor i.e., 35 at this stage is the HCF of 35 and 175.

    Thus, HCF of 105, 140) and 175 is 35.

    Now,

    Number of stacks of Physics books
    equals fraction numerator Number space of space Physics space books over denominator NMumber space of space books space in space each space stack end fraction
equals space 105 over 35 equals 3
    Number of stacks of Chemistry books
    equals fraction numerator Number space of space Chemistry space books over denominator Number space of space books space ineach space stack end fraction
    
equals 140 over 35 equals 4
    Number of stacks of Biology books
    equals fraction numerator Number space of space Biology space books over denominator Number space of space books space in space each space stack end fraction

    equals 175 over 35 equals 5.

    Question 85
    CBSEENMA10006259

    Using Euclid's division algorithm, find the HCF of 56, 96 and 404.

    Solution
    I. By using Euclid's Division Algorithm, we have

    II. Again, we apply division algorithm on divisor 56 and remainder 40, we get

    III. Again, we apply division algorithm on divisor 40 and remainder 16, we get

    IV. Again, we apply division algorithm on divisor 16 and remainder 8, we get

    Now, HCF (56, 96)= 8

    Applying Euclid’s division algorithm on 8 and 404, we get

    Now, HCF (404, 8) = 4

    Hence, H.C.F. of 56, 96 and 404 is 4. Ans.

    Problems Based on Fundamental theorem of Arithmetic

    Question 86
    CBSEENMA10006260

    Find the LCIM and HCF of 6 and 20 by the Prime factorisation method.

    Solution

    Since,    6 = 2 × 3

    and    20 = 2 × 2 × 5

    ∴ LCM = Product of each prime factor with highest powers

    = 22 × 3 × 5 = 60

    i.e., LCM (6,20) = 60

    HCF = Product of common prime factors with lowest powers = 2

    i.e., H.C.F. (6, 20) = 2.

    Question 87
    CBSEENMA10006261

    Find the LCM and HCF of 1296 and 2520 by the prime factorisation method.

    Solution

    Since,

    1296 = 2 × 2 × 2 × 2 × 3 × 3 × 3 × 3

    = 24 × 34

    and    2520 = 2 × 2 × 2 × 3 × 3 × 5 × 7

    = 23 × 32 × 5 × 7

    ∴ LCM = Product of each prime factor with highest powers

    = 24 × 34 × 5 × 7 = 45360

    i.e., LCM (1296, 2520)= 45360

    H.C.F. = Product of common prime factors with lowest powers

    = 23 × 32 = 8 × 9 = 72

    i.e., H.C.F. (1296, 2520) = 72. 

    Question 88
    CBSEENMA10006262

    Find the LCM and HCF of the following integers by applying the prime factorisation method :

    12, 15 and 21

    Solution

    Since, 12 = 2 × 2 × 3 = 22 × 3

    15 = 3 × 5

    and    21 = 3 × 7

    ∴ LCM = Product of each prime factor with highest power

    = 22 × 3 × 5 × 7 = 420

    i.e., LCM (12, 15, 21) = 420

    HCF = Product of common prime factors with lowest powers

    = 3

    i.e., HCF (12, 15,21) = 3.

    Question 89
    CBSEENMA10006265

    Find the HCF of 96 and 404 by the prime factorisation method. Hence, Find their LCM.

    Solution

    Since 96 = 2 × 2 × 2 × 2 × 2 × 3

    = 2s × 3   and    404 = 2 × 2 × 101 = 22 × 101

    ∴ LCM = Product of each prime factor with highest power

    = 2s × 3 × 101 = 9696

    i.e., LCM (96, 404) = 9696

    HCF Product of common prime factors with lowest powers

    = 22 = 4

    We know that,

    HCF (a. b) × LCM (a,b) = a × b

    ⇒ HCF (96, 404) × LMC (96, 404) = 96 × 404

    ⇒ LCM (96, 404)
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#6 {main}</pre>

    Question 90
    CBSEENMA10006267

    Using prime factorization method, Find the LCM of

    (i) 12, 15, 20, 27 (ii) 21, 28, 36, 45.

    Solution
    (i) 12, 15, 20, 27

    Since, 12 = 2 × 2 × 3 = 22 × 3

    15 = 3 × 5

    20 = 2 × 2 × 5 = 22 × 5

    and    27 = 3 × 3 × 3 = 33

    ∴ LCM = Product of each prime factor with highest power

    = 22 × 33 × 5 = 540

    i.e., LCM (12, 15, 20, 27) = 540.

    (ii) 21, 28, 36, 45

     

    Since, 21 = 3 × 7

    28 = 2 × 2 × 7 = 22 × 7>

    36 = 2 × 2 × 3 × 3 = 22 × 32

    and    45 = 5 × 3 × 3 = 5 × 32

    ∴ LCM = Product of each prime factor with highest power

    = 32 × 7 × 22 × 5

    = 1260

    i.e. LCM (21, 28, 36, 45)= 1260.

    Question 91
    CBSEENMA10006268

    There is a circular path around a sports Held. Priya takes 18 minutes to drive one round of the Held, while Ravi takes 12 minutes for the same. Suppose they both start at the same point and at the same time, and go in the same direction. After how many minutes will they meet again at the starting point ?

    Solution
    Required number of minutes is the LCM of 18 and 12. Thus,

    Since, 18 = 2 × 3 × 3 = 2 × 32

    and    12 = 2 × 2 × 3 = 22 × 3

    ∴ LCM = Product of each prime factor with highest power

    = 22 × 32 = 36

    Hence, Ravi and Priya will meet again at the starting point after 36 minutes.

    Question 92
    CBSEENMA10006270

    The sets of Physics, Chemistry and Mathematics books have to be stacked in such a way that all the books are stored topic wise and the height of each stack is the same. The number of Physics books is 12, the number of Chemistry books 20 and the number of Mathematics books is 30. Assuming that the books are of the same thickness, determine the number of stacks of Physics, Chemistry and Mathematics books.

    Solution
    In order to arrange the books as required, we have to find the largest number that divides 12, 20 and30 exactly. Clearly, we have to find HCF. Now,

    Since, 12 = 2 × 2 × 3 = 22 × 3

    20 = 2 × 2 × 5 = 22 × 5

    and    30 = 2 × 3 × 5

    HCF = Product of common prime factors with lowest powers

    = 2

    So, there must be 2 books in each stack.

    ∴ Number of stacks of Physics books
    equals 12 over 2 equals 6
    Number of stacks of Chemistry books
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#6 {main}</pre>
    Number of stacks of Mathematics books
    equals 30 over 2 equals 15

    Question 93
    CBSEENMA10006271

    In a morning walk Nimit, Tanvika and Mehul step off together, their steps measure 84 cm, 90 cm and 120 cm respectively. What is the minimum distance each should walk so that one can cover the distance in complete steps.

    Solution

    Required distance is the LCM of 84 cm, 90 cm and 120 cm.

    Thus,

    Since, 84 = 2 × 2 × 3 × 7 = 22 × 3 × 7

    90 = 2 × 3 × 3 × 5 = 2 × 32 × 5

    and    120 = 2 × 2 × 2 × 3 × 5

    = 23 × 3 × 5

    ∴ LCM = Product of each prime factor with highest power

    = 23 × 32 × 5 × 7 = 2520

    = 25 m 20 cm

    Problems Based on Irrational Numbers

    Question 94
    CBSEENMA10006273

    Prove that square root of 2  is irrational.

    Solution
    Let us assume that  square root of 2 is is rational. We know that, rational number can be written as  space space straight a over straight b comma where ‘a’ and ‘b’ are integers and b ≠ 0. i.e.. Assume that
    square root of 2 equals straight a over straight b
    Squaring both sides
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#6 {main}</pre>
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#6 {main}</pre>

    ⇒ a2 is divisible by 2

    ⇒ a is divisible by 2

    Let a = 2c for some integer c.

    Putting a = 2c in (i), we get

    2 b2 = (2c)2

    ⇒    2b2 = 4c2

    ⇒    b2 — 2c2

    ⇒ b2 is divisible by 2

    ⇒ b is divisible by 2.

    Thus, 2 is a common factor of a and b. But, this contradicts the fact that ‘a’ and ‘b’ have no common factor other than 1.
    The contradiction arises by assuming that  square root of 2 space is rational.
    Hence,  square root of 2 is irrational.


    Question 95
    CBSEENMA10006276

    Prove that square root of 3 is irrational.

    Solution

    Let us assume that square root of 3 is rational.
    We know that rational number can be written as straight a over straight b comma space where ‘a’ and ‘b’ are integers and b ≠ 0.
    i.e., assume that
    square root of 3 equals straight a over straight b
    Squaring both side, we get
    rightwards double arrow space space open parentheses square root of 3 close parentheses squared equals open parentheses straight a over straight b close parentheses squared
rightwards double arrow space space space 3 equals straight a squared over straight b squared
rightwards double arrow space space space space straight a squared equals 3 straight b squared space space space space space space space space space space space space space space space space space space space space space space space space space space space space... left parenthesis straight i right parenthesis

    ⇒ a2 is divisible by 3

    ⇒ a is divisible by 3

    Let a = 3c for some integer ‘c’.

    Putting a = 3c in (i)

    a2 = 3b2

    ⇒    (3c)2 = 3b2

    ⇒    9c2 = 3b2

    ⇒    b2 = 3c2

    ⇒ b2 is divisible by

    ⇒ b is divisible by 3

    Thus, 3 is a common factor of ‘a’ and ‘b’.

    But this contradicts the fact that ‘a’ and ‘b’ have no common factor other than 1.
    The contradiction arises by assuming that square root of 3 is rational.
    Hence,  square root of 3  is irrational.

    Question 96
    CBSEENMA10006279

    Show that <pre>uncaught exception: <b>mkdir(): Permission denied (errno: 2) in /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php at line #56mkdir(): Permission denied</b><br /><br />in file: /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php line 56<br />#0 [internal function]: _hx_error_handler(2, 'mkdir(): Permis...', '/home/config_ad...', 56, Array)
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#6 {main}</pre> is an irrational number.

    Solution

    Let <pre>uncaught exception: <b>mkdir(): Permission denied (errno: 2) in /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php at line #56mkdir(): Permission denied</b><br /><br />in file: /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php line 56<br />#0 [internal function]: _hx_error_handler(2, 'mkdir(): Permis...', '/home/config_ad...', 56, Array)
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#6 {main}</pre> is rational
    i.e., it can be expressed as straight a over straight bwhereas ‘a’ and ‘b’ both are integers and b ≠ 0.
    Thus,  2 minus square root of 3 equals straight a over straight b
    rightwards double arrow space space square root of 3 equals 2 minus straight a over straight b space space space space space.... left parenthesis straight i right parenthesis
    Now straight a over straight b is rational and w'e know that 2 is also rational.
    space
space space space space space space therefore space space 2 space minus straight a over straight b space 
    is also rational
    [∵ Difference, sum and product aftwo rational numbers are always rational]
    Comparing it with result (i), we get square root of 3 is rational, which is not true as square root of 3 is an irrational number.
    ∴ Our assumption that   <pre>uncaught exception: <b>mkdir(): Permission denied (errno: 2) in /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php at line #56mkdir(): Permission denied</b><br /><br />in file: /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php line 56<br />#0 [internal function]: _hx_error_handler(2, 'mkdir(): Permis...', '/home/config_ad...', 56, Array)
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#6 {main}</pre>  is rational is not correct.
    rightwards double arrow space space 2 minus square root of 3 space is space an space irrational.

    Question 101
    CBSEENMA10006285
    Question 108
    CBSEENMA10006293

    Express 0.2317 in the form  straight p over straight q where p and q are co-prime and also express q in the form 22 × 5m.

    Solution
    space space space space space space 0.2317 equals 2317 over 10000
    p=2317 and q = 10000
    Now     q = (10)= (2 x 5)
                 = 2x 5

    we find that 2 and 5 cannot be factors of p = 2317.

    Thus, p = 23 17 and q = 10000 are co-prime.

    Here, q = 24 × 54

    Question 109
    CBSEENMA10006295

    Express 0.737373.......in the form  straight P over straight q

    Solution
    find the prime factorisation of qp and q are co-prime. When?

    rightwards double arrow space space straight a space equals space 0.737373....
rightwards double arrow space space 100 space straight a space equals space 73.737373
space space space space space space space space space space space space space space equals space 73 space plus space straight a
rightwards double arrow space space space space space space space straight a equals 73 over 99 equals straight P over straight q

    rightwards double arrow  p=73 and q = 99 are co-prime.
    Here, q=3X 11.

    Question 110
    CBSEENMA10006300

    Prove that   open parentheses 5 minus 2 square root of 3 close parentheses is an irrational number.  

    Solution
    Let us assume, to the contrary, that   open parentheses 5 minus 2 square root of 3 close parentheses is rational i.e. we can find coprimes a and b (b ≠ 0) such that
    5 minus 2 square root of 3 equals straight a over straight b rightwards double arrow 2 square root of 3 equals 5 minus straight a over straight b equals fraction numerator 5 straight b minus straight a over denominator straight b end fraction
rightwards double arrow space space square root of 3 equals fraction numerator 5 straight b minus straight a over denominator 2 straight b end fraction
    Since a and b are integers, we get
    fraction numerator 5 straight b minus straight a over denominator 2 straight b end fraction is rational, and so space space square root of 3 space is rational
    BUt thisc contradicts the fact that square root of 3  is irrational.

    This contradiction has arises because of our incorrect assumption that  <pre>uncaught exception: <b>mkdir(): Permission denied (errno: 2) in /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php at line #56mkdir(): Permission denied</b><br /><br />in file: /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php line 56<br />#0 [internal function]: _hx_error_handler(2, 'mkdir(): Permis...', '/home/config_ad...', 56, Array)
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#6 {main}</pre>  is an rational.

    Hence, we conclude that  open parentheses 5 minus 2 square root of 3 close parentheses is an irrational number.

    Question 111
    CBSEENMA10006301

    Show that  3<pre>uncaught exception: <b>mkdir(): Permission denied (errno: 2) in /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php at line #56mkdir(): Permission denied</b><br /><br />in file: /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php line 56<br />#0 [internal function]: _hx_error_handler(2, 'mkdir(): Permis...', '/home/config_ad...', 56, Array)
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#6 {main}</pre> is not a rational number.

    Solution

    Sollution not provided.

    Question 112
    CBSEENMA10006302
    Question 113
    CBSEENMA10006303

    Prove that square root of 3 plus square root of 5  is an irrational number.

    Solution

    Sollution is not provided.

    Question 114
    CBSEENMA10006304
    Question 115
    CBSEENMA10006305

    Check whether 12n can end with digit 5 for any n ∊ N.

    Solution

    Sollution is not provided.

    Question 116
    CBSEENMA10006307

     Explain why 11 × 13 × 17 + 17 is a composite number.

    Solution

    Sollution is not provided.

    Question 118
    CBSEENMA10006312

    Sponsor Area

    Question 121
    CBSEENMA10006315

    If straight P over straight q  is a rational number (q = 0), what is the condition on q so that the decimal reprsentation of the straight P over straight q  is terminating?

    Solution

    q is of the form 2m 5n, where m and n are negative integers. (Sollution not provided)
    Question 122
    CBSEENMA10006316
    Question 123
    CBSEENMA10006317

    Write the HCF of the smallest composite number and the smallest prime number.

    Solution

    2,    (Sollution not provided)

    Question 124
    CBSEENMA10006318

    Find the HCF of 960 and 432

    Solution

    (Sollution not provided)

    Question 125
    CBSEENMA10006319

     What is the HCF of 52 and 130.

    Solution

    (Sollution not provided)

    Question 127
    CBSEENMA10006323

    Show that 5 plus 3 square root of 2 is an irrational number.

    Solution

    (Sollution not provided)

    Question 128
    CBSEENMA10006324

    Prove that square root of 5 is an irrational number.

    Solution

    (Sollution not provided)

    Question 129
    CBSEENMA10006325

    Find the [HCF × LCM] for the number 100 and 190.

    Solution

    (Sollution not provided)

    Question 130
    CBSEENMA10006326

    Find the [HCF × LCM] for the number 100 and 190.

    Solution

    (Sollution not provided)

    Question 133
    CBSEENMA10006329
    Question 134
    CBSEENMA10006330
    Question 135
    CBSEENMA10006331

    Prove that 7 plus 3 space square root of 2 is an irrational number.

    Solution

    (Sollution not provided)

    Question 136
    CBSEENMA10006338

    The H.C.F. of 135 and 225 is
    • 135

    • 35

    • 45

    • 65

    Solution

    C.

    45

    Question 137
    CBSEENMA10006350
    Question 139
    CBSEENMA10006355

    space space space 3 plus 2 square root of 5 is a
    • rational number
    • irrational number
    • both (a) and (b)
    • none of these

    Solution

    B.

    irrational number
    Question 140
    CBSEENMA10006357

    6n; n ∊ N cannot end with digit
    • 0
    • 2
    • 8

    Solution

    A.

    0
    Question 141
    CBSEENMA10006369

    
fraction numerator 139 over denominator 2 squared.5 to the power of 7.17 to the power of 5 end fraction space equals space can space be space straight a
    • terminating decimal 
    • non-terminating decimal
    • non-terminating repeating decimal 
    • none of these

    Solution

    C.

    non-terminating repeating decimal 
    Question 145
    CBSEENMA10006392

     8n; n ∊ N cannot ends with :
    • 2

    • 8

    • 0

    • 4

    Solution

    C.

    0

    Question 146
    CBSEENMA10006403
    Question 153
    CBSEENMA10009322

    Which of the following arguments are correct and which are not correct ? Give reasons for your answer.

    Solution

    If a die is thrown once, the possible outcomes are
    S = {1, 2, 3, 4,5, 6} i.e.    n(S) = 6
    Let A be the favourable outcomes of getting add number. Then
    A = {1,3,5} i.e.    n(S) = 3
    Therefore, P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 3 over 6 equals 1 half
    Thus, the given statement is correct.

    Question 154
    CBSEENMA10009323

    Two customers Shyam and Ekta are visiting a particular shop in the same weak (Tuesday to Saturday). Each is equally likely to visit the shop on any day as on another day. What is the probability that both will visit the shop on (i) the same day? (ii) consecutive days? (iii) different days?

    Solution

    Total possible ways of visiting shop by them = 5 x 5 = 25
    (i) They can visit the shop on a 11 week days Tuesday to Saturday.
    Let A be the favourable outcomes of visiting shop by them on the same day = 5 Then, n(A) = 5

     Therefore. P(A)=fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 5 over 25 equals 1 fifth

    (ii) Let Be be the favourable outcomes of visiting shop on the different days by them = 25 – 5 = 20 days.
    i.e.    n(B) = 20
    Therefore, P(B) = fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 20 over 25 equals 4 over 5
    (iii)      Shyam            T         W         Th.       F
               Ekta                W       Th.        F          S
                
               Ekta                T         W         Th.       F
              Shyam             W        Th.        F         S

    Let A be the favourable outcomes of visiting shop on consecutive days.

    Then, n(A) = 8
    Therefore, P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 8 over 25.

    Question 155
    CBSEENMA10009324

    A die is a numbered in such a way that its face show the numbers 1, 2, 2, 3, 3, 6. It is thrown two times and the total score in two throws is noted. Complete the following table which gives a few values of the total score on the two throws :


    What is the probability that the total scene is (i) even, (ii) 6, (iii) at least 6.

    Solution

    Number of possible outcomes = 36
    i.e.    n(S) = 36
    (i) Let A be the favourable outcomes that the total score is even. Then n(A) = 18
    Therefore, P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 18 over 36 equals 1 half.

    (ii) Let B be favourable outcomes that the total score is 6. Then
    n(B) = 4
    Therefore. P(B) = fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 4 over 36 equals 1 over 9.
    (iii) Let C be the favourable outcomes that total score is at least 6. Then n(C) = 15
    Therefore, P(C) = fraction numerator n left parenthesis C right parenthesis over denominator n left parenthesis S right parenthesis end fraction equals 15 over 36 equals 5 over 12.

    Question 156
    CBSEENMA10009325

    A bag contains 5 red balls and some blue balls. If the probability of drawing a blue ball is double that of red ball, find the number of blue balls in the bag.

    Solution

    Number of red balls in the bag = 5 Let number of blue balls in the bag = x Total number of balls in the bag = x + 5 i.e.,    n(S) = x + 5
    Let A be the favourable outcomes of getting red balls, then
    n(A) = 5
    Therefore, P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals fraction numerator 5 over denominator x plus 5 end fraction

    Let B be the favourable outcomes of getting blue balls, then
    n(B) = x
    Therefore, P(B) = fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals fraction numerator x over denominator x plus 5 end fraction
    According to equation,   P(B) = 2 P(A)
    rightwards double arrow   fraction numerator straight x over denominator straight x plus 5 end fraction equals 2 cross times fraction numerator 5 over denominator x plus 5 end fraction
rightwards double arrow space space fraction numerator x over denominator x plus 5 end fraction equals open parentheses fraction numerator 10 over denominator x plus 5 end fraction close parentheses
rightwards double arrow space space space space x space equals space 10
    Hence, the number of blue balls in the bag is 10.

    Question 157
    CBSEENMA10009326

    A box contains 12 balls out of which x are black. If one ball is drawn at random from the box, what is the probability that it will be a black ball? If 6 more black balls are put in the box, the probability of drawing a black ball is now double of what it was before. Find x.

    Solution
    Number of black balls in the box = x
    Total number of balls in the box = 12

    i.e.,    n(S) = 12

    (0 Let A be the favourable outcomes of getting black ball, then
    n(A) = x
    Therefore,
    P(A) = fraction numerator n left parenthesis A right parenthesis over denominator n left parenthesis S right parenthesis end fraction equals x over 12

    (ii) Number of white balls in the box = x + 6 Total number of balls in the box = 12 + 6 = 18. i.e.,    n(S) = 18
    Let B be the favourable outcomes of getting new white balls, then
    n(B) = x + 6
    Therefore,
    P(B) = fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals fraction numerator x plus 6 over denominator 18 end fraction
    Now according to question
    P(B) = 2P(A)
          rightwards double arrow space space space space space space space space space space space space fraction numerator straight x plus 6 over denominator 18 end fraction equals 2 open parentheses x over 12 close parentheses
rightwards double arrow space space space space space space space space space space space space fraction numerator x plus 6 over denominator 18 end fraction equals fraction numerator 2 x over denominator 12 end fraction
rightwards double arrow space space space space space space space space space space space space space fraction numerator x plus 6 over denominator 18 end fraction equals fraction numerator 2 x over denominator 12 end fraction
rightwards double arrow space space space space space space space space space space space space space fraction numerator x plus 6 over denominator 3 end fraction equals x over 6
rightwards double arrow space space space space space space space space space space space space space space fraction numerator x plus 6 over denominator 3 end fraction equals x space
rightwards double arrow space space space space space space space space space space space space space 3 x space equals space x plus 6
rightwards double arrow space space space space space space space space space space space space space space 2 x space equals space 6
rightwards double arrow space space space space space space space space space space space space space space space x space equals space 3 space space space space space space space space space
    Hence, the number of white balls = 3.

    Question 158
    CBSEENMA10009327

    A jar contains 24 marbles, some are green and others are blue. If a marble is drawn at random from the jar, the probability that it is green is 2 over 3 Find the number of blue balls in the jar.

    Solution

    Total number of marbles in the jar = 24
    i.e.    n(S) = 24
    Let number of blue balls in the jar be x.
    Then, the number of green balls in the jar = 24 – x Let A be the favourable outcomes of getting blue balls. Then
    n(A) = x
    Therefore, P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals x over 24

    Let B be favourable outcomes of getting green balls. Then
    n(B) = 24 – x
    Therefore,  P(B) = fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals fraction numerator 24 minus x over denominator 24 end fraction
    According to the given condition :
                    P(B) = 2 over 3
    rightwards double arrow space space space space space space space space fraction numerator 24 minus straight x over denominator 24 end fraction equals 2 over 3
rightwards double arrow space space space space space space space space 3 left parenthesis 24 minus straight x right parenthesis space equals space 2 space straight x space 24
rightwards double arrow space space space space space space space space 72 minus 3 straight x equals 48
rightwards double arrow space space space space space space space space minus 3 straight x space equals space 48 minus 72
rightwards double arrow space space space space space space space space plus 3 straight x space equals space minus 24
rightwards double arrow space space space space space space space space space space space space straight x space equals space 8 space
    Hence, the number of blue balls in the jar = 8.

    Question 159
    CBSEENMA10009328

    A box contains cards marked with numbers 5 to 20. A card is drawn from the bag at random. Find the probability of getting a number which is a perfect square.

    Solution

    Total number of possible outcome(s) are 16 i.e.,    n(S) = 16

    Let A be the favourable outcomes of getting getting a number which is perfect square. Then A = (9,16) i.e.,    n(A) = 2

    Therefore,
    rightwards double arrow space space space space straight P left parenthesis straight A right parenthesis space equals space fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 2 over 16 equals 1 over 8

    Question 160
    CBSEENMA10009329

    A die is thrown once. Find the probability of getting number less than 3.

    Solution

    When a die is thrown oner then possible outcome(s) are 6
    i.e.,    n(S) = 6
    Let A be the favourable outcomes of setting a number less than 3. then
    A = (1,2) i.e.,    n(A) = 2
    Therefore,

    Question 161
    CBSEENMA10009330

    A die is thrown once. Find the probability of getting number less than 5.

    Solution

    When a die is thrown once, then possible outcome(s) are 6
    i.e.,    n(S) = 6
    Let ‘A’ be the favourable outcomes of getting a number greater than 5. Then A = (6) i.e.,    n(A) = 1
    Therefore,


    rightwards double arrow space space space straight P left parenthesis straight A right parenthesis space equals space fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 1 over 6.

    Question 162
    CBSEENMA10009331

    What is the probability that a number selected have the number 1,2,3..............,15 is a multiple of 4.

    Solution

    Here, we have S = {1, 2, 3,....., 15}
    ⇒    n(s) = 15
    Let A be the favourable av + causes of getting a multiple 4, then A = {4,8,12}
    ⇒     n (A) = 3
    Therefore, P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 3 over 15 equals 1 fifth.

    Question 163
    CBSEENMA10009332

    Write the Sample Space when a coin is tossed.

    Solution

    S = {H, T}

    Question 164
    CBSEENMA10009333

    Two friends were bom in the year 2000. What is the probability that they have the same birthday?

    Solution

    2000 is a leap year. So, their birthday can be any day of 366 days in the year. We assume that these 366 outcomes are equally likely. Because both the friends have the same birthday.

    ∴ Favourable outcomes for their birthday = 1 Hence, P (both have the same birthday)
    equals space 1 over 366

    Question 165
    CBSEENMA10009334

    Which of the following can not be the probability of an event?

    left parenthesis straight i right parenthesis space 2 over 3 space space space space left parenthesis ii right parenthesis space space minus 1.5 space space space space space left parenthesis iii right parenthesis space 15 percent sign space space space left parenthesis iv right parenthesis space 0.7

    Solution

    As we know probabilty of event can not be less than O and greater than 1.
    i.e. O ≤ P ≤ 1
    ∶ (B) –1.5 is not possible.

    Question 167
    CBSEENMA10009336

    One card is drawn from a well shuffled deck of 52 cards. Calculate the probability that the card will be a ‘diamond’?

    Solution

    If a card is drawn from a well shuffled deck of 52 cards, then possible outcomes (3) are 52 i.e. n(s) = 52
    Let A be the favourable outcomes of setting a diamond then.
    A = {13} i.e.    (A) = 13
    Therefore,
    straight P left parenthesis straight A right parenthesis space equals space fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 13 over 52 equals 1 fourth.

    Question 168
    CBSEENMA10009337

    A bag contains 4 red and 6 black balls. A ballis taken out of the bag of random. Find the probability of setting a black ball.

    Solution
    No. of red balls = 4 No. of black balls = 6 Total no. of balls = 4 + 6 = 10 Let A be the favourable outcomes of setting a black ball, then, n(A) = 6 Therefore,
    straight P left parenthesis straight A right parenthesis equals fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 6 over 10 equals 3 over 5.
    Question 169
    CBSEENMA10009338

    From a well suoffled pack of cards, a card is drawn at random. Find the probability of setting a black queen.

    Solution

    When a Card is drawn of random from a well shoffled pack of cards, then possible outcomes are 52.
    i.e. n(s) = 52
    Let A be the favourbale outcomes of setting a black queen, then n(A) = 2 Therefore,
    P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 2 over 52 equals 1 over 26

    Question 170
    CBSEENMA10009339

    Cards bearing numbers 3 to 20 are placed in a bag and mixed thoroughly. A card is taken out from the bag at random. What is the probability that the number on the card taken out is an even number.

    Solution

    Total no. of possible outcome(s) are 18. i.e.,    n(S) =18
    Let A be the favourable outcomes of getting the number on the card which is an even number, then
    A = (4,6,8,10,12,14,16,18,20) i.e.,    m(A) = 9
    Therefore,
    rightwards double arrow   P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 9 over 18 equals 1 half

    Question 171
    CBSEENMA10009340

    A die is thrown once. Find the probablity of setting ‘a’ prime number.

    Solution

    If a die is thrown once, then
    S = {1,2,3,4,5,6} i.e. n(s) = 6
    Let A be favourable outcomes of setting a prime number, then
    A = {2,3,5} i.e.    n(4) = 3
    Therefore, P(A) = fraction numerator n left parenthesis A right parenthesis over denominator n left parenthesis S right parenthesis end fraction equals 3 over 6 equals 1 half

    Question 172
    CBSEENMA10009341

    A die is thrown once. Find the probability of gettings ‘a number divisible by 2.’

    Solution

    If a die is thrown once, then S = {1,2,3,4,5,6} i.e.    n( s) = 6
    Let A be the favourable outcomes of setting number divisible by 2. then
    A = {2,4,5} i.e.    n(A) = 3
    Therefore,  P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 3 over 6 equals 1 half.

    Question 173
    CBSEENMA10009342

    A die thrown once. Find the probability of getting
    (i)    an even prime number
    (ii)    a multiple of 3

    Solution

    If a die thrown once then possible outcomes are
    S = {1, 2, 3, 4, 5, 6} i.e. n(S) = 6
    (i) Let A be the favourable outcomes of getting an even prime number, then
    A = [2] i.e. n(A) = 2
    Therefore, P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 1 over 6

    (ii) Let B be the favourable outcomes of getting a multiple of three, then
    B = {3,6} i.e. n(B) = 2
    Therefore, P(B) = fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 2 over 6 equals 1 third

    Question 176
    CBSEENMA10009345

    What is the combine probability of a favorable and unfavorable event.

    Solution

    Solution not provided.
    Ans. 1

    Question 177
    CBSEENMA10009346

    If P (E) 0.58 write P(E)

    Solution

    Solution not provided.
    Ans. 0.42

    Question 178
    CBSEENMA10009347

    If E is an event such that P(E) = 2 over 7 write 1 - P open parentheses top enclose straight E close parentheses.

    Solution

    Solution not provided.
    Ans. 2 over 7

    Question 179
    CBSEENMA10009348

     If probability of success is 34%. What is the probability of failure.

    Solution

    Solution not provided.
    Ans. 66%

    Question 181
    CBSEENMA10009350
    Question 189
    CBSEENMA10009358
    Question 190
    CBSEENMA10009359
    Question 191
    CBSEENMA10009360

    Find the probability of getting a head when a coin is tossed once. Also find the probability of getting a tail.

    Solution

    If we toss a coin then we get either a head or a tail. Thus number of possible outcomes(s) are two–Head(H) and Tail(T).
    i.e.,    S = |HT|
    ⇒    n(S) = 2
    Let E be the favourable outcomes of getting head, then
    E = {H}
    ⇒    n(E) = 1
    Therefore,  P(E) P(Head) = fraction numerator straight n left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 1 half

    Let F is the favourable outcomes of getting Tail, then
    F = {T}
    ⇒        n(F) = 1
    Therefore,  P(F) = P(Tail) =  fraction numerator straight n left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 1 half

    Note : For any event E, P(E) + P(Ē) = 1.
    Where Ē stands for‘note’E and Ē are called complementary favourable events.

     
    Question 192
    CBSEENMA10009361

    A pair of coin is thrown once. Find the probability of (i) One Head, (ii) Two Tails.

    Solution

    If we toss a pair of coins twice then we get following possible outcomes (S).
    i.e.,    S = { HT, TH, HH, TT }
    ⇒    n(S) = 04
    Let E be the favourable outcomes of getting one head, then
    E = { HT, TH }
    ⇒    n(E) = 2
    Therefore,  P(E) = fraction numerator straight n left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 2 over 4 equals 1 half

    Let F is the favourable outcomes of getting two tails, then
    F = { T, T }
    ⇒    n(F) = 1
    Therefore,    P(F) = fraction numerator straight n left parenthesis straight F right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 1 fourth.

    Question 193
    CBSEENMA10009362

    Two coins are tossed simultaneously. Find the probability of getting.
    (i) two heads, (ii) at least one head, (iii) no head.

    Solution

    If we toss two coins simultaneously, then possible out comes (s), are
    S = { HT, TH, HH, TT }
    ⇒    n( S) = 4
    Let E be the favourable outcomes of getting two heads, then
    E = { H H }
    ⇒    n(E) = 1
    Therefore,   P(E) = fraction numerator straight n left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 1 fourth

    Let F be the favourable outcomes of getting at least one head, then
    F = { HH, HT, TH }
    ⇒    n(F) = 3
    Therefore,   P(F) = fraction numerator straight n left parenthesis straight F right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 3 over 4

    Let G be the favourable outcomes of getting no head then
    ⇒    n (G) = 1
    Therefore,   P(G) = fraction numerator straight n left parenthesis straight G right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 1 fourth.

    Question 194
    CBSEENMA10009363

    Two unbiased coins are tossed once. What is the probability of getting exactly one head.

    Solution

    If we toss two unbiased coins, then possible outcomes(s), are
    S = { HH, TH, TT, HT }
    ⇒    n(S) = 4
    Let A be the favourable outcomes of getting exactly one head, then
    A = {TH, HT } i.e.,    n( A) = 2
    Therefore,      P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 2 over 4 equals 1 half.

    Question 195
    CBSEENMA10009364

    Justify the statement: “Tossing a coin is a fair way of deciding which team should get the batting first at the beginning of a cricket game.”

    Solution
    The result of an individual coin is completely unpredictable. Hence, both the team gets equal chance to bat first so that the given statement is justified.
    Question 196
    CBSEENMA10009365

    A die is thrown once, find the probability of getting a prime number.

    Solution

    If we throw a die once then possible outcomes (s) are
    S = {1, 2, 3, 4, 5, 6}
    ⇒    n(S) = 6
    Let E be the favourable outcome of getting a prime number then
    E = 12, 3, 5}
    ⇒    irt(E) = 3
    Therefore,   P(E) = fraction numerator straight n left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 3 over 6 equals 1 half

    Question 197
    CBSEENMA10009366

    A die is rolled once, find the probability of getting a number greater than 2.

    Solution

    If we roll a die once, then possible outcomes (s), are
    S = (1, 2, 3, 4, 5, 6)
    ⇒    n( S) = 6
    Let E be the favourable outcomes of getting a number greater than 2, then E = { 3, 4, 5, 6, }
    ⇒ n(E) = 4
    Therefore,  P(E) = fraction numerator straight n left parenthesis straight E right parenthesis over denominator nm left parenthesis straight S right parenthesis end fraction equals 4 over 6 equals 2 over 3

    Question 198
    CBSEENMA10009367

    A die is thrown once. What is the probability of getting a number 5 or 6?

    Solution

    If we throw a die once, then possible outcomes (s), are
    S = {1, 2, 3, 4, 5, 6}
    ⇒    n(S) = 6
    Let E be the favourable outcomes of getting a number 5 or 6, then
    E = (5, 6}
    ⇒    n (E) = 2
    Therefore,  P(E) = fraction numerator straight n left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 2 over 6 equals 1 third.

    Question 199
    CBSEENMA10009368

    A die is thrown once. Find the probability of getting
    (i)    an even number.
    (ii)    a number greater than 3.
    (iii)    a number between 3 and 6.

    Solution

    If we throw a die once, then possible outcomes (s), are
    S = { 1, 2, 3, 4, 5, 6 }
    ⇒    n(E) = 6
    (i) Let E be the favourable outcomes of getting an even number, then
    E = { 2, 4, 6 }
    ⇒ n(S) = 3
    Therefore, P(E) = fraction numerator straight n left parenthesis straight F right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 3 over 6 equals 1 half

    (ii) Let F be the favourable outcomes of getting a number greater than 3, then
    F = { 4, 5, 6 }
    ⇒    n( F) = 3
    Therefore,  P(E) = fraction numerator straight n left parenthesis straight F right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 3 over 6 equals 1 half

    (iii) Let G be the favourable outcomes of getting a number between 3 and 6.
    G = { 4, 5 }
    ⇒    n(G) = 2
    Therefore,  P(G) = fraction numerator straight n left parenthesis straight G right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 2 over 6 equals 1 third.

    Question 200
    CBSEENMA10009369

    A die is thrown once. Find the probability of getting
    (i) an odd number.
    (ii) a number greater than 4.
    (iii) seven.

    Solution

    If we throw a die once, then possible outcomes (s) are,
    S = { 1, 2, 3, 4, 5, 6 )
    n(S) = 6
    (i) Let F be the favourable outcomes of getting an odd number, then
    E = { 1, 3, 5 }
    ⇒ n(E) = 3
    Therefore,  P(E) = fraction numerator straight n left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 3 over 6 equals 1 half

    (ii) Let F be the favourable outcomes of getting a number greater than 4, then F = {5, 6}
    ⇒    n(F) = 2
    Therefore,  P(F) = fraction numerator straight n left parenthesis straight F right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 2 over 6 equals 1 third

    (iii) Let G be the favourable outcome of getting seven, then
    G = { 0 }
    ⇒    n(G) = 0
    Therefore,   P(G) = fraction numerator straight n left parenthesis straight G right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 0 over 6 equals 0

    Question 201
    CBSEENMA10009370

    A die is thrown once. Find the probability of getting
    (i)    a prime number
    (ii)    a number divisible by 2

    Solution

    (i) If a die is thrown once, then possible outcomes are

    S {1, 2, 3, 4, 5, 6} i.e. n(S) = 6 Let A be the favourable outcomes of setting a prime number, than A = {2, 3, 5} i.e. n(A) = 3 Therefore,
    P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 3 over 6 equals 1 half
    (ii) Let B be the favourbale outcomes of setting a number divisibel by 2, then B = {2, 4, 6} i.e. n(B) - 3
    Therefore, P(B) = fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 3 over 6 equals 1 half

    Question 202
    CBSEENMA10009371

    Two dice are thrown simultaneously. Find the probability that the sum of the two numbers appearing on the top is less than or equal to 10.

    Solution

    Let A be the favourable outcomes of getting the sum of the two numbers appearing on the top is less than or equal to 10, then

    A = (1,1), (1,2), (1,3), (1,4), (1,5), (1,6)

    (2.1),    (2,2), (2,3), (2,4), (2,5), (2,6)

    (3.1),    (3,2), (3,3), (3,4), (3,5), (3,6)

    (4.1),    (4,2), (4,3), (4,4), (4,5), (4,6)

    (5.1),    (5,2), (5,3), (5,4), (5,5)

    (6.1),    (6,2), (6,3)/ (6,4) i.e., n( A) = 33

    Therefore,  
    rightwards double arrow space space space space space space space space straight P left parenthesis straight A right parenthesis space equals space fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 33 over 36 equals 11 over 12

    Question 203
    CBSEENMA10009372

    A pair of dice is thrown once. Find the probability of getting a total of 5 on two dice.

    Solution

    If a pair of dice is thrown once, then possible outcomes(s) are 36. i.e.,    n(S) = 36
    Let E be the favourable outcomes of getting a total of 5 on two dice, then
    E = {(1, 4), (2, 3), (3, 2), (4,1)}
    ⇒    n(E) = 4
    Therefore,   P(E) = fraction numerator straight N left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 4 over 36 equals 1 over 9

    Question 204
    CBSEENMA10009373

    A pair of dice is thrown once. Find the probability of getting the same number on each dice. 

    Solution

    When a pair of dice is thrown once then possible outcome(s) are 36. i.e.,    n( S) = 36
    Let A be the favourable outcomes of getting the same number of each dice, then
    S= ((1,1), (1,2), (1,3), (1,4), (1,5), (1,6)
    (2.1),    (2,2), (2,3), (2,4), (2,5), (2,6)
    (3.1),    (3,2), (3,3), (3,4), (3,5), (3,6)
    (4.1),    (4,2), (4,3), (4,4), (4,5), (4,6)
    (5.1),    (5,2), (5,3), (5,4), (5,5), (5,6)
    (6.1),    (6,2), (6,3), (6,4), (6,5), (6,6)}
    ⇒ (A) = {(11), (2,2), (3,3), (4,4), (5,5), (6,6))
    i.e. n( A)= 6
    Therefore,
    rightwards double arrow space space space space P left parenthesis A right parenthesis equals fraction numerator n left parenthesis A right parenthesis over denominator n left parenthesis S right parenthesis end fraction equals 6 over 36 equals 1 over 6

    Question 205
    CBSEENMA10009374

    Two dice are thrown simultaneously. What is the probability that
    (i) 5 will not come up on either of them?
    (ii) 5 will come up on at least one?
    (iii) 5 will come at both dice?

    Solution
    (i) Let A be the favourable outcomes that 5 will not come up on either of them Then

    i.e. n(A) = 25
    Therefore,   = 25 over 36

    (ii) Let B be the favourable outcomes that 5 will come up on at least one dice. Then
    B = {(1,5), (2, 5), (3, 5), (4, 5), (5,1),
    (5,2), (5, 3) (5, 4), (5,5), (5, 6), (6,5)}
    i.e., n(B) = 11
    Therefore,  P(B) = 11 over 36

    (iii) Let C be the event that 5 will come up on both the dice.
    C = {5, 5}, i.e., n(C) = l
    Therefore,  P(C)=1 over 30

    Question 206
    CBSEENMA10009375

    Two dice are thrown simultaneously. Find the probability of getting :
    (i) a sum less than 6 (ii) a sum less than 7
    (iii) a sum more than 7 (iv) 8 as the sum

    Solution

    If two dice are thrown simultaneously, then possible outcomes(s) are 36. i.e., n(S)= 36
    (i) Let E be the favourable outcomes of getting a sum less than 6, then
    E= {(1,1),(1, 2), (l, 3), (1,4), (2, 1), (2, 2), (2, 3), (3, l), (3, 2), (4, l)}
    ⇒ n(E)= 10 Therefore,
    P(E) = fraction numerator straight n left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 10 over 36 equals 5 over 18

    (ii) Let F be the favourable outcomes of getting a sum less than 7.
    F= {(1, 1), (1, 2), (1,3), (1,4), (1,5). (2, 1), (2, 2), (2, 3), (2, 4), (3, 1), (3, 2), (3, 3), (4,1), (4, 2), (5, 1)}
    ⇒ n( F)=15 Therefore,
    P(F) = fraction numerator straight n left parenthesis straight F right parenthesis space over denominator straight n left parenthesis straight S right parenthesis end fraction equals 15 over 36 equals 5 over 12

    (iii) Let G be the favourable outcomes of getting a sum more than 7, then
    G = {(2, 6), (3, 5), (3, 6), (4, 4), (4, 5), (4, 6), (5, 3), (5, 4), (5, 5), (5, 6), (6, 2), (6, 3), (6, 4), (6, 5), (6, 6)1
    ⇒ n(G) = 15 Therefore,
    P(G) = fraction numerator straight n left parenthesis straight G right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 15 over 36 equals 5 over 12

    (iv) Let H be the favourable outcomes of getting 8 as the sum. then
    H = |(2, 6), (3, 5), (4, 4), (5, 3), (6, 2)}
    ⇒ n( H) = 6 Therefore.
    P(H) = fraction numerator n left parenthesis H right parenthesis over denominator n left parenthesis S right parenthesis end fraction equals 5 over 36

    Question 207
    CBSEENMA10009376

    A deck of 52 cards is shuffled. Tanvika draws a single card from the deck at random. What is the probability that the card is a Jack.

    Solution

    If a deck of 52 cards is shuffled then sample space is 52. i.e., n(S) = 52
    Let E be the favourable outcomes of getting Jack, then
    n(E) = 4 Therefore,
    straight P left parenthesis straight E right parenthesis equals fraction numerator straight n left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 4 over 52 equals 1 over 13.

    Question 208
    CBSEENMA10009377

    A card is drawn from a pack of 52 playing cards. What is the probability that it is

    (i) an ace
    (ii)    a face card
    (iii)    any card numbered from 2 to 10?

    Solution

    Total number of all possible outcomes = 52
    i.e., n( S) = 52
    (i) Let E be the favourable outcomes of getting an ace, then
    n(E) = 4 Therefore,
    P(E) = fraction numerator straight n left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 4 over 52 equals 1 over 13.

    (ii) Let F be the favourable outcomes of getting a face card, then
    n(F) = 12 Therefore,
    P(F) = fraction numerator straight n left parenthesis straight F right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 12 over 52 equals 3 over 13

    (iii) Let G be the favourable outcomes of getting any card numbered from 2 to 10, then n(G)= {36}

    Therefore,
    P(G) = fraction numerator straight n left parenthesis straight G right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 36 over 52 equals 9 over 13.

    Question 209
    CBSEENMA10009378

    One card is drawn from a pack of 52 cards, each of the 52 cards being equally likely to be drawn. Find the probability that the card drawn is :
    (i) red    (ii) either red or king
    (iii) red and a king (iv) a red face card
    (v) ‘2’ of spades (vi) ‘10’ of a black suit.

    Solution

    Total number of all possible outcomes = 52.
    i,e,. n(S)=52
    (i) Let B be the favourable outcomes of getting red,then
    n (B) = 26.
    Therefore, P(B) = 26 over 52 equals 1 half.

    (ii) Let C be the favourable outcomes of getting a card either red or king, then n(C)= 28.

    Therefore,  P(C) = fraction numerator straight n left parenthesis straight C right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 28 over 52 equals 7 over 13
    (iii) Let D be the favourable outcomes of getting red and a king, then n(D)=2 Therefore,
    P(D) = fraction numerator straight n left parenthesis straight D right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 2 over 52 equals 1 over 26.

    (iv) Let E be the favourable outcomes of getting a red face card, then
    n(E) = 6
    Therefore,  P(E) = fraction numerator straight n left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 6 over 52 equals 3 over 36.

    (v) Let F be the favourable outcomes of getting 2 of spades, then
    E = {1}
    ⇒    n(E) = 1
    Therefore,  P(E) = fraction numerator straight n left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 1 over 52.

    (vi) Let G be the favourable outcomes of getting 10 of black suit then ⇒
    n(G) = 2
    Therefore,  P(G) = fraction numerator straight n left parenthesis straight G right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 2 over 52 equals 1 over 26.
     

    Question 210
    CBSEENMA10009379

    A card is drawn at random from a well-shuffled deck of playing cards. Find the probability of drawing a (i) face card (ii) Card which is neither a king nor a red card.

    Solution

    f one card is drawn from a well-shuffled deck of playing card, then possible outcome(s) are (52)
    i.e.,    n(S) = 52
    I. Let A be the favourable outcomes of getting a face card, then
    i.e.,    n(A) = 12
    Therefore,
    rightwards double arrow space straight P left parenthesis straight A right parenthesis space equals fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 12 over 52 equals 3 over 13

    II. Let B be the favourable outcomes of getting card which is neither a king nor a red card, then i.e.,    n(B) = 24

    Therefore,

     rightwards double arrow space space straight P left parenthesis straight B right parenthesis equals fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 24 over 52 equals 6 over 13
    Question 211
    CBSEENMA10009380

    One card is drawn from a well-shuffled deck of 52 cards. Find the probability of getting

    (i)      a king of red colour.
    (ii)     a face card.
    (iii)    a blackface card.
    (iv)    a Jack of hearts.
    (v)     a spade
    (vi)    a queen of diamond.

    Solution

    Total number of all possible outcomes = 52
    i.e., n(S) = 52
    (i) Let E be the favourable outcomes of getting a king of red colour, then n(E)= 2 Therefore,
    P(E) = fraction numerator straight n left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 2 over 52 equals 1 over 26

    (it) Let F be the favourable outcomes of getting a face card, then
    n(F) = 12
    Therefore,
    P(F) = fraction numerator straight n left parenthesis straight F right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 12 over 52 equals 3 over 13

    (iii) Let G be the favourable outcomes of a red face card, then
    n(G) = 6
    P(G) = fraction numerator straight n left parenthesis straight G right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 6 over 52 equals 3 over 26

    (iv) Let H be the favourable outcomes of getting a jack from the hearts, then n( H) = 1
    Therefore,
    P(H) = fraction numerator straight n left parenthesis straight H right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 1 over 52

    (v) Let I be the favourable outcomes of getting a spade, then
    n(I) = 13
    Therefore:
    P(l) = fraction numerator straight n left parenthesis straight I right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 13 over 52 equals 1 fourth

    (vi) Let J be the favourable outcomes of getting a queen of diamonds, then n(J) = 1

    Therefore,
    P(J) = fraction numerator straight n left parenthesis straight J right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 1 over 52.

    Question 212
    CBSEENMA10009381

    Five cards - the ten, jack, queen, king and ace of diamonds are well-shuffled with their face down wards. One card is then picked up at random.
    (i)    What is the probability that the card is a queen?
    (ii)    If the queen is drawn and put aside, what is the probability that the second card picked up is (a) an ace (b) a queen.

    Solution

    It is given that the total number of cards = 5
    i.e.    n(S) = 5
    (i) Let E be the favourable outcomes of getting a queen, then
    E = {1}
    ⇒    n(E) = 1
    Therefore,
    P(E) = fraction numerator straight n left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 1 fifth

    (ii) If the Queen is drawn and put aside then possible outcomes become 4 i.e.,    n(S) = 4
    (a) Let A be the favourable outcomes that the picked up card is an ace, then n(A) = {1}

    Therefore,
    P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 1 fourth

    (b) Let B be the favourable outcomes that the picked up card is a queen, then n(B) = 0

    Therefore,
    P(B) = fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 0 over 4 equals 0

    Question 213
    CBSEENMA10009382

    The king, queen and jack of clubs are removed from a deck of 52 cards and then well shuffled. One card is selected from the remaining cards. Find the probability of getting
    (i) a heart (ii) a kitty (iii) a club (iv) the 1O' of heart. 

    Solution

    If the king, queen and jack of clubs are removed from a deck of 52 cards, then possible outcomes become 49.
    i.e.,    n(S) = 49 [52 –3 = 49]
    (i) Let E be the favourable outcomes of getting a heart, then
    n (E) = 13 Therefore,
    P(E) = fraction numerator straight n left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 13 over 49

    (ii) Let F be the favourable outcomes of getting a king then,
    n(F) = 3
    Therefore,
    P(F) = fraction numerator straight n left parenthesis straight F right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 3 over 49

    (iii) Let G be the favourable outcomes of getting a club, then
    n(G) = 10
    Therefore,
    P(G) = fraction numerator straight n left parenthesis straight G right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 10 over 49

    (iv) Let H be the favourable outcomes of getting the 10 of hearts, then n(H) = 1
    Therefore,
    P(H) = fraction numerator straight n left parenthesis straight H right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 1 over 49


    Question 214
    CBSEENMA10009383

    If 2 black kings and 2 red aces are removed from a deck of 52 cards, find the probability of getting

    (i)    ati ace of heart
    (ii)    a king
    (iii)    a ace
    (iv)    a heart
    (v)    a red card

    Solution

    If 2 black kings and 2 red aces are removed from a deck of 52 cards, then possible outcomes are 52 – 4 = 48
    i.e.    n (S) = 48
    (i) Let E be the favourable outcomes of getting an ace, then
    n(E) = 0
    Therefore,
    P(E) = fraction numerator straight n left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 0 over 48 equals 0

    (ii) Let F be the favourable outcomes of getting an ace, then
    n(F) = 2
    Therefore,
    P(F) = fraction numerator straight n left parenthesis straight F right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 2 over 48 equals 1 over 24

    (iii) Let G be the favourable outcomes of getting a king, then
    n(G) = 2
    Therefore,

     P(G) = fraction numerator straight n left parenthesis straight G right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 2 over 48 equals 1 fourth
    (iv) Let H be the favourable outcomes of getting a heart, then H = {Total red cards - one red card which is removed) i.e., n (H) = 12 Therefore,
    p(H) = fraction numerator straight n left parenthesis straight H right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 12 over 48 equals 1 fourth

    (v) Let 1 be the favourable outcomes of getting a red card, then,
    n(I) = 24
    Therefore,
    P(I) = fraction numerator straight n left parenthesis straight I right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 24 over 48 equals 1 half

    Question 215
    CBSEENMA10009384

    A card is drawn at random from a pack of 52 cards. Find the probability that the card drawn is

    (i)    n black king
    (ii)    either a black card or a king
    (iii)    black and a king
    (iv)    a jack, queen or a king
    (v)    neither a heart nor a king
    (vi)    spade or an ace

    (vii)    neither an ace nor a king.

    Solution

    Total number of all possible outcomes = 52.
    i.e.,    n( S) = 52
    (i) Let A be the favourable outcomes of getting a black king, then
    n( A) = 2
    Therefore,
    P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 2 over 52 equals 1 over 26

    (ii) Let B be the favourable outcomes of getting either a black card or a king, then n(B) = 28
    Therefore,
    P(B) = fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 28 over 52 equals 7 over 13

    (iii) Let C be the favourable outcomes of getting black and a king, then n(C) = 2
    Therefore,
    P(C) = fraction numerator straight n left parenthesis straight C right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 2 over 52 equals 1 over 26

    (iv) Let D be tine favourable outcomes of getting a jack, queen or a king then n(D) = 12
    Therefore,
    P(D) = fraction numerator n left parenthesis D right parenthesis over denominator n left parenthesis S right parenthesis end fraction equals 12 over 52 equals 3 over 13

    (v) Let E be the favourable outcomes of getting neither a Heart nor a king, then n(E) = 36
    Therefore,
    P(E) = fraction numerator straight n left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 36 over 52 equals 9 over 13

    (vi) Let F be the favourable outcomes of getting spade or an ace, then
    n(F) = 16
    Therefore,
    P(F) = fraction numerator straight n left parenthesis straight F right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 16 over 52 equals 4 over 13

    (vii) Let G be the favourable outcomes of getting neither an ace nor a king, then n(G) = 44
    Therefore,
    P(G) = fraction numerator straight n left parenthesis straight G right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 44 over 52 equals 11 over 13

    Question 216
    CBSEENMA10009385

    A king, queen and jack of diamonds are removed from a pack of 52 cards and then the pack is well-shuffled. A card is drawn from the remaining cards. Find the probability of getting a card of (i) diamonds, (ii) a jack.

    Solution

    When a king, queen and jack of diamonds are removed from a pack of 52 cards, then possible outcome(s)are
    52–3 = 49 i.e.,    n(S) = 49
    I. Let A be the favourable outcomes of getting a card of diamonds. Then i.e.,    n( A) = 10
    Therefore,
    rightwards double arrow space space space space space straight P left parenthesis straight A right parenthesis space equals space fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 10 over 49

    II. Let B be the favourable outcomes of getting a jack, then
    i.e.,    n(B) = 3
    Therefore, 

    rightwards double arrow space space space space space space straight P left parenthesis straight B right parenthesis space equals space fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 3 over 49

    Question 217
    CBSEENMA10009386

    All the three cards of spades are removed from a well-shuffled pack of 52 cards. A card is drawm at random from the remaining pack. Find the probability of getting.
    (a) a black face card (b) a queen (c) a black card.

    Solution

    If all the three face cards of spades are removed, then possible outcome(s) are 49. i.e.,    n(S) = 49
    (a) Let A be the favourable outcomes of getting a black face card, then n (A) = 3
    Therefore,
    P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 3 over 49
    (b) Let B be the favourable outcomes of getting a queen, then
       
                 n(B) = 3
    Therefore,    P(B) = fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 3 over 49

    (c) Let C be the favourable outcomes of getting a black card, then
    n(C) = {23}
    Therefore,    P(C) = fraction numerator straight n left parenthesis straight C right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 23 over 49

    Question 218
    CBSEENMA10009387

    Red kings, queens and jacks are removed from a deck of 52 playing cards and then well shuffled. A card is drawn from the remaining cards. Find the probability of getting
    (i) a king, (ii) a red card, (iii) a spade.

    Solution

    If Red kings, queens and jacks are removed from a deck at 52 cards, then n(S) = 52
    (i) Let ‘A’ be the favourable outcomes of getting a king, then
    n(A) = 02
    Therefore,  P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 02 over 42 equals 1 over 21
    (ii) Let 'B' be the favourable outcomes of getting 'a red card' their
                   n(B) = 20
    Therefore,  P(B) = fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 20 over 42 equals 10 over 21
    (iii) Let 'C' be the favourable outcomes of getting 'a spade'. Then
                  n(C) = 11
    Therefore, P(C) = fraction numerator straight n left parenthesis straight C right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 11 over 42

    Question 219
    CBSEENMA10009388

    All cards of ace, jack and queen are removed from a deck of playing cards. One card is drawn at random from the remaining cards, find the probability that the card drawn is

    (a)    a face card
    (b)    not a face card

    Solution

    Out of 52 cards all cards of ace, jack and queen are removed.
    So, remaining cards = 52 – 12 = 40 i.e., n(S) = 40
    (a) Let E be the favourable outcomes of getting face cards, then
    E= {total face cards - face cards which are removed}
    E = {12-8} i.e.,    n(E) = 4
    Now, P (getting face cards)
    equals space fraction numerator straight n left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 4 over 40 equals 1 over 10

    (b) Let 'F' be the favourable outcomes of getting 'not a face card', then
    F = {40 – 4} i.e.,    n( F) = 36
    Now, P (getting not a face card)
    equals space fraction numerator straight n left parenthesis straight E right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 36 over 40 equals 9 over 10

    Question 220
    CBSEENMA10009389

    A bag contains 5 red, 4 blue and 3 green balls. A ball is taken out of the bag at random. Find the probability that the selected ball is (0 of red colour (ii) not green colour.

    Solution

    No. of red colour balls = 5
    No. of blue colour balls = 4
    No. of green colour balls = 3
    Total no. of balls    = 12
    i.e.,    n( S) = 12
    I. Let ‘A’ be the favourable outcomes of getting ‘of red colour’. Then,
    i.e., n( A) = 5
    Therefore,
    rightwards double arrow space space space space space straight P left parenthesis straight A right parenthesis space equals space fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 5 over 12

    II. Let 'B' be the favourable outcomes of getting not of green colour. Then
    i.e.,    n( B) = 9
    Therefore,

    rightwards double arrow space space space space space straight P left parenthesis straight B right parenthesis space equals space fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 9 over 12 equals 3 over 4.

    Question 221
    CBSEENMA10009390

    A bag contains 4 red, 5 black and 3 yellow balls. A ball is taken out of the bag at random. Find the probability that the ball taken out is of (i) yellow colour (ii) not of red colour.

    Solution

    No. of red balls    = 4
    No. black balls    = 4
    No. of yellow balls    = 3
    Total no. of balls (4+5+3) = 12 n(S) = 12
    I. Let ‘A’ be the favourable outcomes of getting the ball taken out is of ‘yellow colour’ 1 hen
    n( A) = 3
    Therefore,
    rightwards double arrow space space space space space space straight P left parenthesis straight A right parenthesis space equals space fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 3 over 12 equals 1 fourth

    II. Let ‘B’ be the favourable outcomes of getting the ball taken out is of ‘not of red colour’ I hen,
    i.e.,    n(B) = 8
    Therefore,
    rightwards double arrow space space space space straight P left parenthesis straight B right parenthesis space equals space fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 8 over 12 equals 2 over 3

    Question 222
    CBSEENMA10009391

    A bag contains 5 red balls, 8 white balls, 4 green balls and 7 black balls. If one ball is drawn at random, find the probability that it is (i) black, (ii) red, (iii) not green.

    Solution

    No. of red balls in the bag = 5
    No. of white balls in the bag = 8
    No. of black balls in the bag = 7
    No. of green balls in the bag = 4
    Total no. of balls in the bag = 24
    i.e.,    n(S) = 24
    (i) Let ‘A’ be die favourable outcomes of getting black ball, then
    i(A) = 7
    Therefore,
    P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight m left parenthesis straight S right parenthesis end fraction equals 7 over 24

    (ii) Let B' be the favourable outcomes of getting red balls, then
    n(B) = 5
    Therefore,
    P(B) = fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 5 over 24

    (iii) Let ‘C’ be the favourable outcomes of getting a ball ‘not green’ then n(C) = 20
    Therefore,
    P(C) = fraction numerator straight n left parenthesis straight C right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 20 over 24 equals 5 over 6.

    Question 223
    CBSEENMA10009392

    A bag contains 5 red balls and some blue balls. If the probability of drawing a blue ball from the bag is four times that of a red ball. Find the number of blue balls in the bag.

    Solution

    Number of red balls in the bag = 5
    Let number of blue balls in the bag = x
    Now, total number of balls in the bag = x + 5
    i.e.,    n( S) = n + 5
    (i) Let ‘A’ be the favourable outcomes of getting blue balls, then
    n( A) = x
    Therefore,
    P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals fraction numerator x over denominator x plus 5 end fraction

    (i) Let 'B' be the favourable outcomes of getting red balls, then
    n(B) = 5
    Therefore,
    P(B) = fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals fraction numerator x over denominator x plus 5 end fraction
    According to question :
        P(A) = 4 P (B)
    rightwards double arrow space space space space fraction numerator straight x over denominator straight x plus 5 end fraction equals 4 open parentheses fraction numerator 5 over denominator straight x plus 5 end fraction close parentheses
rightwards double arrow space space straight x space equals space 20
    Hencem the number of blue balls in the bag is 20.

    Question 224
    CBSEENMA10009393

    A box contains 5 red balls, 4 green balls and 7 white balls. A ball is drawn at random from the box. Find the probability that the ball drawn is
    (a) White (b) neither red nor white

    Solution

    Number of red balls in the box = 5
    Number of green balls in the box = 4
    Number of white balls in the box = 7
    Total number of balls in the box = 16
    i.e., n (S) = 16
    (i) Let A be the favourable outcomes of getting white balls, then
    n(A) = 7
    Therefore,
    P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 7 over 16
    (ii) Let B be the favourable outcomes of getting neither red nor white balls, then
    n(B) = 1 - P (red or white)
           = 1 - [P (red) + P (white)]
            equals space 1 space minus open square brackets 5 over 16 plus 7 over 16 close square brackets
equals space 1 minus 12 over 16 equals 4 over 16 equals 1 fourth

    Question 225
    CBSEENMA10009394

    A bag contains 5 red, 8 green and 7 white balls. One ball is drawn at random from the bag, find the probability of getting

    (i) white ball or a green ball.
    (ii) neither a green ball not a red ball.

    Solution

    Total number of balls in the bag = 5 + 8 + 7 = 20
    i.e.    n( S) = 20
    (i) Let A be the favourable outcomes of getting a white ball or a green ball. Then n( A) = 15
    Therefore,
    P(getting a white ball or a green ball)
    equals fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 15 over 20 equals 3 over 4

    (ii) Let B be the favourable outcomes of getting neither of a green ball nor a red ball. Then h(B) = 7
    Therefore, P(getting neither a green ball nor a red ball)
    equals space fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 7 over 20.

    Question 226
    CBSEENMA10009395

    Cards marked with the numbers 2 to 101 are placed in a box and mixed throughly. One card is drawn from this box. Find the probability that the number on the cards is
    (i)    an even number
    (ii)    a number less than 14.
    (iii)    a number which is a perfect square.
    (iv)    a prime n umber less than 20.

    Solution

    (i) Total no. of cards = 100
    i.e., n( S)= 100

    (ii) Let A be the favourable outcomes of getting an even number, then
    A = {2,4,6,8,10........100}
    ⇒    n( A) = 50
    Therefore,
    straight P left parenthesis straight A right parenthesis space equals space fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 50 over 100 equals 1 half

    (ii) Let B be the favourable outcomes of getting a number less than 14, then
    B = {2,3,4,5,6...........13}
    ⇒    n(B) = 12
    Therefore,
    straight P left parenthesis straight B right parenthesis space equals space fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 12 over 100 equals 3 over 25

    (iii) Let C be the favourable outcomes of getting a number which is a perfect square, then
    C = {4,9,16,25,36,49,64,81,100}
    ⇒ n(C) = 9 Therefore,
    straight P left parenthesis straight C right parenthesis space equals space fraction numerator straight n left parenthesis straight C right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 9 over 100

    (iv) Let D be the favourable outcomes of getting a prime number less than 20, then
    D = {2,3,5,7,11,13,17,19}
    ⇒    n(D) = 8
    Therefore,
    straight P left parenthesis straight D right parenthesis equals fraction numerator straight n left parenthesis straight D right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 8 over 100 equals 2 over 25

    Question 227
    CBSEENMA10009396

    18 Cards, numbered 1, 2, 3, ..., 18 are put in a box and mixed throughly. A card is drawn at random from the box. Find the probability that the Card drawn bears
    (i)    an even number
    (ii)    a number divisible by 2 or 3

    Solution

    Total number of cards 18 i.e., n( S) = 18
    (i) Let A be the favourable outcomes of getting an even number, then
    A= { 2. 4, 6, 8, 10, 12, 14, 16, 18 }
    ⇒ n(A) = 9 Therefore,
    straight P left parenthesis straight A right parenthesis equals fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 9 over 18 equals 1 half

    (ii) Let B be the favourable outcomes of getting a number divisible by 2 or 3 then, N(B) = 12
    Therefore,

    straight P left parenthesis straight B right parenthesis space equals space fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 12 over 18 equals 2 over 3

    Question 228
    CBSEENMA10009397

    12 cards, numbered 1, 2,3......., 12 are put in a box and mixed throughly. A card is drawn at random from the box. Find the probability that the card drawn bears

    (i)    an even number
    (ii)    a number divisible by 2 or 3.

    Solution

    (i) Let A be the favourable outcomes of getting an even number, then
    A = {2,4,6,8,10,12}
    ⇒    n( A) = 6
    Therefore,
    straight P left parenthesis straight A right parenthesis space equals space fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 6 over 12 equals 1 half

    (it) Let B be the favourable outcomes of getting  number divisible by 2 or 3, then n(B) ='8
    Therefore,
    straight P left parenthesis straight B right parenthesis equals fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 8 over 12 equals 2 over 3

    Question 229
    CBSEENMA10009398

    Out of 400 bulbs in a box, 15 bulbs are defective. One bulb is taken out at random from the box. Find the probability that the drawn bulb is not defective.

    Solution

    TotaLnumbers of bulbs = 400 i.e.    n{S) = 400
    Let A be the favourable outcomes of getting 'non defective bulb', then
    n(A) = 385
    Therefore,
    straight P left parenthesis straight A right parenthesis equals fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 385 over 400 equals 77 over 80.

    Question 230
    CBSEENMA10009399

    What is the probability that a leap year, selected at random will contain 53 sundays?

    Solution

    A leap year has 366 days, i.e., 52 weeks and 2 days.
    The remaming 2 days can be
    (i)    Sunday and Monday.
    (ii)    Monday and Tuesday.
    (iii)    Tuesday and Wednesday.
    (iv)    Wednesday and Thursday.
    (v) Thursday and Friday.
    (vi)    Friday and Saturday.
    (vii)    Saturday and Sunday.
    Out of these seven possibilities only tw'o are favourable for Sunday.
    Hence, probability of getting 53 Sundays in a leap year = 2 over 7.

    Question 231
    CBSEENMA10009400

    A bag contains tickets, number 11,12, 13......30. A ticket is taken out from the bag at random, find the probability that the number on the drawn ticket is (0 a multiple of 7, (ii) greater than 15 and a multiple of 5.

    Solution

    Total no. of tickets =20 Le.,    n(S) = 20
    I. Let ‘A’ be the favourable outcomes of getting a multiple of 7, then
    A = (14,21,28)
    i.e.,    n( A) = 3
    Therefore,
    rightwards double arrow space space space space straight P left parenthesis straight A right parenthesis space equals space space fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 3 over 20

    II. Let ’B' be the favourable outcomes of getting the number greater than 15 and multiple of 5, then B = (20,25,30) i.e.,    n(B) = 3

    Therefore,
    rightwards double arrow space space space space space straight P left parenthesis straight B right parenthesis space equals space fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 3 over 20

    Question 232
    CBSEENMA10009401

    Cards marked with numbers 3,4, 5,.....,50 are placed in a box and mixed throughly. One card is drawn at random from the box. Find the probability that number on the drawn card is
    (i)    divisible by 7
    (ii)    a number which is a square.

    Solution

    Total number of cards 48
    i.e.,    n(S) = 48
    (i) Let A be the favourable outcomes of getting a numbers divisible 7, then
    A = {7,14,21,28,35,42,49}
    ⇒    n(A) = 7
    Therefore,  
    P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 7 over 48

    (ii) Let B be the favourable outcomes of getting number a which is a perfect square, then
    B = {4, 9, 16, 25, 36, 49)
    ⇒    n(B) = 6
    Therefore,
    P(B) = fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 6 over 48 equals 1 over 8.

    Question 233
    CBSEENMA10009402

    Cards each marked with one of the numbers 6, 7, 8,....., 15 are placed in a box and mixed thoroughly. One card is drawn at random from the box. What is the probability of getting a card with number less than 10?

    Solution

    Total no. of cards : 10 i.e., n(S) = 10
    Let A be the favourable outcomes of getting a card with numbers less than 10, then
    A = {6, 7, 8, 9}
    i.e., n(A) = 4
    Therefore,
    P(A) = fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 4 over 10 equals 2 over 5.

     
    Question 234
    CBSEENMA10009403

    Two dice are thrown at the same time. Find the probability that the sum of the two numbers appearing on the top of the dice is more than 9. 

    Solution

    If two dice are thrown at the same time, then possible outcomes are 36.
    i.e.,    n( S) = 36.
    Let A be the favourable outcomes of getting the sum of two numbers appearing on the top of the dice is more than ? They
    A = {(4,6), (5,5), (6,4), (5, 6), (6,5), (6,6)}
    i.e.,    n( A) = 6
    Therefore,
    straight P left parenthesis straight A right parenthesis space equals space fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals 6 over 36 equals 1 over 6

    Question 235
    CBSEENMA10009404

    A box has cards numbered 14 to 99. Cards are mixed thoroughly and a card is drawn from the bag at random. Find the probability that the number on the card, drawn from the box is

    (i)     an odd number,
    (ii)    a perfect square number,
    (iii)   a number divisible by 7.

    Solution

    Total no. of cards = 86, i.e., n(S) = 86

    (i) Let A be the favourable outcomes of getting an odd number. Then,
    A = {15,17,19,21,23,25,27,29,31,33,35, 37, 39,41,43,45,47,49, 51,53, 55,57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99}
    n( A) = 43
    Therefore,
    P(A)= nAnS=4386 = 12

    (ii) Let B be the favourable outcomes of getting a perfect square number. Then,
    B = {16, 25,36, 49, 64,81) i.e., n(B) = 6
    Therefore,
    P(B)=n(B)n(S)=686 = 343

    (iii) Let C be the favourable outcomes of getting a number divisible by 7. Then
    C = {14,21,28,35,42,49,56,63,70,77,84, 91,98}
    i.e., n( C) = 13
    Therefore,
    P(C)=n(C)n(S)=1386

    Question 239
    CBSEENMA10009408
    Question 240
    CBSEENMA10009409

    Two coins are tossed once simultaneously, find the probability write the elements of the sample space.

    Solution

    Solution not provided.
    Ans.    S = [HH, HT, TH, TT]

    Question 244
    CBSEENMA10009413
    Question 245
    CBSEENMA10009414
    Question 246
    CBSEENMA10009415

    An unbiased die is thrown once. Find the probability of getting
    (i) an even number and a multiple of 3. (ii) an even number or a multiple of 3.

    Solution

    Solution not provided.
    Ans.   (i)  2 over 3    (ii) 1 over 6

    Tips: -

    Problems Based on Die
    Question 247
    CBSEENMA10009416

    An unbiased die is thrown once. Find the probability of getting:
    (i)    a multiple of 2 or 3.
    (ii)    2 or 4.

    Solution

    Solution not provided.
    Ans.  (i) 2 over 3   (ii)  1 third

    Tips: -

    Problems Based on Die
    Question 248
    CBSEENMA10009417

    A die is thrown once. What is the probabilty of getting a number 5 or 6.

    Solution

    Solution not provided.
    Ans.  1 third

    Tips: -

    Problems Based on Die
    Question 249
    CBSEENMA10009418

    An unbiased die is thrown once. Find the probability of getting seven.

    Solution

    Solution not provided.
    Ans.  0

    Question 254
    CBSEENMA10009423
    Question 255
    CBSEENMA10009424

    A die is thrown once. What is the probability of getting a number other ghan 3.
    Problems Based on Two Dice

    Solution

    Solution not provided.

    Ans.   5 over 6

    Tips: -

    Problems Based on Die
    Question 256
    CBSEENMA10009425

    Two dice are thrown. Find the probability that a multiple of 2 occurs on one dice and a multiple of 3 occurs on other.

    Solution

    Solution not provided.
    Ans.   11 over 36

    Tips: -

    Problems Based on Die.
    Question 257
    CBSEENMA10009426

    Find the probability of throwing (a) 3, (b) an even number with an ordinary six faced dice.

    Solution

    Solution not provided.
    Ans.   left parenthesis a right parenthesis space space 1 over 6 space space left parenthesis b right parenthesis space 1 half space space space

    Tips: -

    Problems Based on Die.
    Question 258
    CBSEENMA10009427

     Two dice are thrown simutaneously. Find the probability of getting six as the product.

    Solution

    Solution not provided.
    Ans.   1 over 9

    Tips: -

    Problems Based on Die.
    Question 261
    CBSEENMA10009430

    In a single throw of a two dice, find the probability that neither a doublet nor a total of 9 will appear.

    Solution

    Solution not provided.
    Ans.    13 over 18

    Tips: -

    Problems Based on Die.
    Question 262
    CBSEENMA10009431

    A pair of dice is thrown once. Find the probability that neither a doublet nor a total of 7 will appear.

    Solution

    Solution not provided.
    Ans.    2 over 3

    Tips: -

    Problems Based on Die.
    Question 263
    CBSEENMA10009432

    A pair of dice is thrown once, find the probability of getting  a number greater than 5 on each dice.

    Solution

    Solution not provided.
    Ans.    1 over 36

    Tips: -

    Problems Based on Die.
    Question 264
    CBSEENMA10009433
    Question 265
    CBSEENMA10009434

    A die is thrown once. Find the probability of getting:
    (i) a number greater than 6.
    (ii) a number between 4 and 6.

    Solution

    Solution not provided.
    Ans.    (i) 0  (ii) 1 over 6

    Tips: -

    Problems Based on Die.
    Question 267
    CBSEENMA10009436

    A card is drawn from a well shuffled pack of 52 cards. Find the probability that it is neither an ace nor a king.

    Solution

    Solution not provided.
    Ans.   11 over 13

    Tips: -

    Problems Based on Cards
    Question 270
    CBSEENMA10009439
    Question 272
    CBSEENMA10009441

    One card is drawn from a well shuffled deck of 52 cards. Find the probability of getting '6' or '7' or 8 of red suit.

    Solution

    Solution not provided.
    Ans.  3 over 26

    Tips: -

    Problems Based on Cards
    Question 285
    CBSEENMA10009454

    The probability of winning a game is 0.3. What is the probability of loosing it?

    Solution

    Solution not provided.
    Ans.   0.7

    Question 287
    CBSEENMA10009456

    What is the probability that a leap year have 53 Mondays.

    Solution

    Solution not provided.
    Ans.   2 over 7

    Question 289
    CBSEENMA10009458
    Question 290
    CBSEENMA10009459
    Question 291
    CBSEENMA10009460
    Question 300
    CBSEENMA10009469
    Question 316
    CBSEENMA10009485

    Find the probability of getting 53 Fridays in a leap year.

    Solution

    Solution not provided.
    Ans.  2 over 7

    Question 337
    CBSEENMA10009506
    Question 341
    CBSEENMA10009510
    Question 343
    CBSEENMA10009512

    A die is thrown once. Find the probability of getting a number less than 3.

    Solution

    Solution not provided.
    Ans.     1 third

    Question 346
    CBSEENMA10009515
    Question 352
    CBSEENMA10009602

    Three different coins are tossed together. Find the probability of getting
    (i) exactly two heads
    (ii) at least two heads
    (iii) at least two tails.

    Solution

    When three coins are tossed together, the possible outcomes are
    HHH, HTH, HHT, THH, THT, TTH, HTT, TTT
    therefore,
    Total number of possible outcomes = 8
    (i) Favourable outcomes of exactly two heads are HTH, HHT, THH
    Total number of favourable outcomes= 3
    Probability of getting exactly two heads = 3/8
    (ii) Favourable outcomes of at least two heads are HHH, HTH, HHT, THH
    Total number of favourable outcomes =4
    Probability of getting at least two heads =4/8 = 1/2

    (iii)Favourable outcomes of at least two tails are THT, TTH, HTT, TTT
    Total number of favourable outcomes =4
    Probability of getting at least two tails - 4/8 = 1/2

    Question 353
    CBSEENMA10009610

    A number x is selected at random from the numbers 1, 2, 3, and 4. Another number y is selected at random from the numbers 1, 4, 9 and 16. Find the probability that product of x and y is less than 16.

    Solution

    x is selected from 1,2,3 and 4
    1,2,3,4
    y is selected from 1,4,9 and 16
    Let A {1,4,9,16,2,8,18,32,3,12,27,48,36,64} which consists
    of elements that are product of x and y
    straight P left parenthesis space product space of space straight x space and space straight y space is space less space than space 16 right parenthesis space equals space fraction numerator Number space of space outcomes space less space than space 16 over denominator Total space number space of space outcomes end fraction
space equals space 7 over 14
equals 1 half

    Question 354
    CBSEENMA10009616

    The different dice are tossed together. Find the probability that the product of the two number on the top of the dice is 6.

    Solution

    When two dice are thrown simultaneously, the possible outcomes can be listed as:

     

    1

    2

    3

    4

    5

    6

    1

    (1, 1)

    (1, 2)

    (1, 3)

    (1, 4)

    ( 1, 5)

    (1, 6)

    2

    (2, 1)

    (2, 2)

    (2, 3)

    (2, 4)

    (2, 5)

    (2, 6)

    3

    (3, 1)

    (3, 2)

    (3, 3)

    (3, 4)

    (3, 5)

    (3, 6)

    4

    (4, 1)

    (4, 2)

    (4, 3)

    (4, 4)

    (4, 5)

    (4, 6)

    5

    (5, 1)

    (5, 2)

    (5, 3)

    (5, 4)

    (5, 5)

    (5, 6)

    6

    (6, 1)

    (6, 2)

    (6, 3)

    (6, 4)

    (6, 5)

    (6, 6)


    ∴ Total number of possible outcomes = 36
    The outcomes favourable to the event the product of the two number of the top of the dice is 6 denoted by E are (1, 6), (2, 3), (3, 2) and (6, 1)
    ∴ Number of favourable outcomes = 4
    straight P space left parenthesis space straight E right parenthesis space equals space fraction numerator Favourable space number space of space outcomes over denominator Total space number space of space outcomes end fraction
equals space 4 over 36

space equals space 1 over 9

    Question 355
    CBSEENMA10009628
    Question 356
    CBSEENMA10009641

    A card is drawn at random from a well-shuffled deck of playing cards.

    (i) a card of a spade or an ace.
    (ii) a black king
    (iii) neither a jack nor a king
    (iv) either a king or queen

    Solution

    Total number of cards = 52
    (i) Number of cards that are spades or aces  = 13 + 3 = 16
    Probability that the card  drawn is a card of spade or an ace
     =  fraction numerator Favourable space number space of space outcomes over denominator Total space number space of space outcomes end fraction space equals space 16 over 52 space equals space 4 over 13 
    (ii) Number of black kings = 2
    Probability that the card  drawn is a black king 

    fraction numerator Favourable space number space of space outcomes over denominator Total space number space of space outcomes end fraction space 2 over 52 space equals space 1 over 26
    (iii) Number of cards that are neither jacks nor kings = 52 - 8 = 44
    Probability that the card drawn is neither a jack nor a king 
     =  fraction numerator Favourable space number space of space outcomes over denominator Total space number space of space outcomes end fraction space equals space 44 over 22 space equals space 11 over 13
    (iv) Number of cards that are kings or queens = 4 + 4 = 8
    Probability that the card drawn is either a king or queen 
     = fraction numerator Favourable space number space of space outcomes over denominator Total space number space of space outcomes end fraction space equals 8 over 52 space equals space 2 over 13

    Question 357
    CBSEENMA10009680

    What is the HCF of the smallest prime number and the smallest composite number?

    Solution

    Smallest prime number is 2.

    Smallest composite number is  4

    therefore, HCF is 2

    Question 358
    CBSEENMA10009688

    Given that 2 is irrational, prove that (5 + 32) is an irrational number.

    Solution

    Let us assume that ( 5 + 32) is rational. Then there exist co-prime positive integers a and b such that
     5 +32 = ab32 = ab-52 = a-5b3b 2 is rational[ a, b are integers,  a- 5b3b is rational]

    This contradicts that 2 is irrational.
    So our assumption is incorrect.

    Hence, (5 + 32) is an irrational number.

    Question 359
    CBSEENMA10009692

    Find HCF and LCM of 404 and 96 and verify that HCF × LCM = Product of the two given numbers.

    Solution

    Using the factor tree for the prime factorization of
    404 and 96, we have
    404 = 22× 101 and 96 = 25 × 3

    To find the HCF, we list common prime factors and their smallest exponent in 404 and 96 as under: Common prime factor = 2, Least exponent = 2
    therefore, HCF = 22 =4

    To find the LCM, we list all prime factors of 404 and 96 and their greatest exponent as follows:

    Prime factors of 404 and 96 Greatest Exponent
    2 5
    3 1
    101 1

    Therefore,

    LCM = 25 x 31 x 1011

     = 25 x 31 x 1011

     = 9696
    Now, 

    HCF x LCM = 9696 x 4= 38784
    Product of two numbers = 404 x 96
    Therefore, HCF x LCM = Product of two numbers.

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