Aptitude - Ratio and Proportion
Overview Exercise "I do not seek. I find."
- Pablo Picasso
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: 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
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: E
Explanation:
Let the original salaries of Ravi and Sumit be Rs. 2x and Rs. 3x respectively.
Then,
2x + 4000
=
40
3x + 4000
57
x + 4000) = 40(3x + 4000)
x = 68,000
x = 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:
Answer: E
Explanation:
(x x 5) = (0.75 x 8) x =
6
= 1.20
5
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:
Answer: E
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
24
= 10 : 15 : 24
5
The required ratio =
: 
: 
, then the first part is: