Mathematical Operations Questions

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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421 71055
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 /
 
Answer & Explanation Answer: B) - 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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439 50289
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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495 37844
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
 
Answer & Explanation Answer: B) -, +, x

Explanation:

Clearly 5 - 0 + 3 X 5 = 20

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203 32958
Q:

The solution of 3(2u + v) = 7 uv and 3(u + 3v) = 11 uv is _____

 

A) u = 1, v = 0 B) u = 1, v = 3/2
C) u = 0, v = 3/4 D) u = 0, v = 1
 
Answer & Explanation Answer: B) u = 1, v = 3/2

Explanation:

Using Trial and error method,

From the options  u = 1, v = 3/2 satisfies both the equations.

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43 26538
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
 
Answer & Explanation Answer: A) A

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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53 26501
Q:

What should come in place of the question mark(?) in the following questions ?

316 + 412 - 223 - 11112 = ?

A) 1 7/12 B) 1 5/12
C) 3 7/12 D) 3 1/12
 
Answer & Explanation Answer: D) 3 1/12

Explanation:

? = (3 + 4 - 2 - 1) + ( 1/6 + 1/2 - 2/3 - 11/12) 

= 4 + [(2+6-8-11)/12] 

= 4 - (11/12 )= 31/12.

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87 24515
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.

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193 23574