CBSE mathematics

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Question
CBSEENMA10009714

The angle of depression of a car, standing on the ground, from the top of a 75 m high tower, is 30o. The distance of the car from the base of the tower (in m.) is

  • 253

  • 503

  • 753

  • 150

Solution

C.

753

WiredFaculty

Let AB be the tower of height 75 m and C be position of the car.

In 

ABC,cot 30°= ACABAC=AB cot 30°AC=75m x 3AC=753mThus, the distance of the car from the base of the tower is 753 m. 

Sponsor Area

Question
CBSEENMA10009715

The probability of getting an even number, when a die is thrown once, is

  • 12

  • 13

  • 16

  • 56

Solution

A.

12

S = { 1, 2, 3, 4, 5, 6 }

let event E be defined as 'getting an even number'.

n(E) = { 2, 4, 6 }

  P(E) = Number of favourable outcomesNumber of possible outcomes =36                  = 12

Question
CBSEENMA10009716

A box contains 90 discs, numbered from 1 to 90. If one disc is drawn at random from the box, the probability that it bears a prime-number less than 23,is

  • 790

  • 1090

  • 445

  • 989

Solution

C.

445

S = { 1, 2, 3,........90 }

n(s) = 90

The prime number less than 23 are 2, 3, 5, 7, 11, 13, 17 and 19

Let event E be defined as 'getting a prime number less than 23'.

n(E) = 8

 p(E) =Number of favourable outcomesNumber of possible outcomes = 890               =445

Question
CBSEENMA10009717

If the difference between the circumference and the radius of a circle is 37cm, then using π = 227 , the circumference (in cm) of the circle is:

  • 154

  • 44

  • 14

  • 7

Solution

B.

44

Let r be the radius of the circle,

From the given information, we have

2πr - r =37 cm r ( 2π - 1 ) = 37 cm r  2 x 227 - 1 = 37 cm   r x 377 = 37 cm r = 7 cm Circumference of the circle = 2πr = 2 x 227 x 7 cm = 44 cm

Question
CBSEENMA10009718

The common difference of AP 13q. 1-6q3q, 1-12q3q, ........ is;1 1 6q 1 12q, , 3q 3q 3q
... is:

  • q

  • -q

  • -2

  • 2

Solution

C.

-2

 Comman difference = 1 - 6q3q - 13q = 1-6q-13q = -6q3q = -2