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Mathematical Operations And Symbol Notations

More Topic from Reasoning

Question 1
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 In this question, some equations are solved on the basis of a certain system. On the same basis find out the correct answer from amongst the four alternatives for the unsolved equation.
3 x 4 x 5 = 435,   4 x 3 x 2 = 342,      2 x 3 x 4 = ?

  • 324

  • 242

  • 432

  • 243

Solution

A.

324

See the pattern:
3 x 4 x 5 = 435, (write second digit on first place and first digit on second place and third digit remains unchanged).
Similarly,
2 x 3 x 4 =  324 (write second digit on first place and first digit on second place and third digit remains unchanged).

Question 2
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A*B means multiply A by B; A@B means divide A by B, A ? B means add B to A and A=B means subtract B from A. Then find the value of 10*10 = 5*10 ? 50 @10.

  • 100

  • 45

  • 1000

  • 55

Solution

D.

55

10*10 = 5*10 ? 50 @ 10
      equals space 10 space cross times space 10 space minus space 5 space cross times space 10 space plus space 50 space divided by space 10 space equals space 100 space minus space 50 space plus space 5 equals space 50 plus 5 equals space 55        

Question 3
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After interchanging + and −, 8 and 7, which one of the following becomes correct?

  • 8 − 7 + 3 x 5 = 35

  • 8 x 2 + 7 − 6  = 9

  • 7 x 8 + 6 − 9  = 25

  • 6 + 8 x 2 − 7  = 0

Solution

D.

6 + 8 x 2 − 7  = 0

As in option (d), we can see.
                     6 + 8 x 2 − 7 = 0
                     6 − 7 x 2 + 8 = 0

Question 4
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If '+' means 'x' , '−' means '÷' 'x' means '−' and '÷' means '+',  then find the value of the following equation.
6 + 64 − 8 ÷ 45 x 8 

  • 85

  • 76

  • 87

  • 75

Solution

A.

85

Given equation
      6 + 64 − 8 ÷ 45 x 8 
Now, changing the sign as per the instruction
      6 x 4 ÷ 8 + 45 − 8
       equals space fraction numerator 6 space cross times space 64 over denominator 8 end fraction plus 45 space minus space 8 space space equals space 6 space cross times space 8 space plus 45 space minus space 8 space equals space 48 space plus space 45 space minus space 8 space equals space 93 space minus space 8 space equals space 85

Question 5
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If '+' means subtraction, '÷' means addition, '<' means multiplication and '>' means division, then find the value of the given statement, 9 ÷ 7 < 8 > (4>2) + 5 

  • 32

  • 18

  • 16

  • 11

Solution

A.

32

 9 ÷ 7 < 8 > (4>2) + 5 
On changing signs, 
 = 9 + 7 x 8 ÷ (4 ÷ 2) - 5
 = 9 + 7 x  8 ÷ 2 - 5
 = 9 + 7 x 4 - 5
 = 9 + 28 - 5
 = 37 - 5 = 32
 
 

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