# Mathematical Operations Questions

Q:

If A + B = 2C and C + D = 2A, then

 A) A + C = B + D B) A + C = 2D C) A + D = B + C D) A + C = 2B

Answer & Explanation Answer: A) A + C = B + D

Explanation:

Given,

A + B = 2C ----(i)

C + D = 2A----(ii)

Adding (i) and (ii) we get : A + B + C + D = 2C + 2A

=>  B + D = A + C

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Q:

Given interchanges :

Signs + and - , numbers 4 and 8.

 A) 4 + 8 - 12 = 12 B) 4 - 8 + 12 = 0 C) 8 + 4 - 12 = 24 D) 8 - 4 + 12 = 8

Answer & Explanation Answer: B) 4 - 8 + 12 = 0

Explanation:

On interchanging + and - and 4 and 8 in (b),

we get the equation as

8 + 4 - 12 = 0
or 12 - 12 = 0
or 0 = 0, which is true.

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Q:

Find out the two signs to be interchanged for making following equation correct

5 + 3 x 8 - 12 / 4 =3

 A) + and - B) - and / C) + and x D) + and /

Explanation:

On interchanging - and /, we get the equation as

5 + 3 x 8 / 12 - 4 = 3

or 5 + 3 x (2/3) - 4 = 3

or 3 = 3, which is true.

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Q:

If × stands for 'addition', ÷ stands for 'subtraction', + stands for 'multiplication' and-stands for 'division', then 20 × 8 ÷ 8 - 4 + 2 = ?

 A) 80 B) 25 C) 24 D) 5

Explanation:

By the Given data , We have the expression:

20 + 8 - 8 ÷ 4 × 2 = 20 + 8 - 2 × 2 = 20 + 8 - 4 = 24.

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Q:

Select the correct set of symbols which will fit in the given equation?

5  0  3  5 = 20

 A) x, x, x B) -, +, x C) x, +, x D) +, -, x

Explanation:

Clearly 5 - 0 + 3 X 5 = 20

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Q:

12:30 :: 14: ?

 A) 36 B) 28 C) 35 D) 42

Explanation:

Here 12 x 2.5 = 30

In the same way 14 x 2.5 = 35

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Q:

Find the quadratic equations whose roots are the reciprocals of the roots of $2x2+5x+3$?

A)  $3x2+5x+2=0$

B) $5x2+3x+2=0$

C) $3x2-5x-2=0$

D)  None

 A) A B) B C) C D) D

Explanation:

The quadratic equation whose roots are reciprocal of $2x2+5x+3=0$ can be obtained by replacing x by 1/x.

Hence, 2(1/x)(1/x)+ 5(1/x) + 3 = 0

=> $3x2+5x+2=0$

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Q:

Given intercharges :

Signs + and x and numbers 4 and 5.

 A) 5 x 4 + 20 = 40 B) 5 x 4 + 20 = 85 C) 5 x 4 + 20 = 104 D) 5 x 4 + 20 = 95

Answer & Explanation Answer: C) 5 x 4 + 20 = 104

Explanation:

On interchanging + and x and 4 and 5 in (c),

we get the equation as
4 + 5 x 20 = 104 or 104 = 104, which is true.