Ratio and Proportion aptitude questions

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6. The ratio of the number of boys and girls in a college is 7 : 8. If the percentage increase in the number of boys and girls be 20% and 10% respectively, what will be the new ratio?
A. 8 : 9 B. 17 : 18
C. 21 : 22 D. Cannot be determined

Answer: Option C

Explanation:

 

Originally, let the number of boys and girls in the college be 7x and 8x respectively.

Their increased number is (120% of 7x) and (110% of 8x).

 

120 x 7x and 110 x 8x
100 100

 

42x and 44x
5 5

 

The required ratio = 42x : 44x = 21 : 22.
5 5
7. Salaries of Ravi and Sumit are in the ratio 2 : 3. If the salary of each is increased by Rs. 4000, the new ratio becomes 40 : 57. What is Sumit’s salary?
A. Rs. 17,000 B. Rs. 20,000
C. Rs. 25,500 D. Rs. 38,000

Answer: Option D

Explanation:

 

Let the original salaries of Ravi and Sumit be Rs. 2x and Rs. 3x respectively.

 

Then, 2x + 4000 = 40
3x + 4000 57

57(2x + 4000) = 40(3x + 4000)

6x = 68,000

3x = 34,000

Sumit’s present salary = (3x + 4000) = Rs.(34000 + 4000) = Rs. 38,000.
8. If 0.75 : x :: 5 : 8, then x is equal to:
A. 1.12 B. 1.2
C. 1.25 D. 1.30

Answer: Option B

Explanation:

 

 

(x x 5) = (0.75 x 8)    x = 6 = 1.20
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9. The sum of three numbers is 98. If the ratio of the first to second is 2 :3 and that of the second to the third is 5 : 8, then the second number is:
A. 20 B. 30
C. 48 D. 58

Answer: Option B

Explanation:

 

Let the three parts be A, B, C. Then,

 

A : B = 2 : 3 and B : C = 5 : 8 = 5 x 3 : 8 x 3 = 3 : 24
5 5 5

 

A : B : C = 2 : 3 : 24 = 10 : 15 : 24
5

 

B = 98 x 15 = 30.
49
10. If Rs. 782 be divided into three parts, proportional to : : , then the first part is:
A. Rs. 182 B. Rs. 190
C. Rs. 196 D. Rs. 204

Answer: Option D

Explanation:

 

Given ratio = : : = 6 : 8 : 9.

 

1st part = Rs. 782 x 6 = Rs. 204
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