Get your age calculations right with ratio and proportion

This article is in continuation to the last article focusing on the ratio and proportion topic

Hyderabad: This article is in continuation to the last article focusing on the ratio and proportion topic. Here are some practice questions along with solutions on the ratio and proportion topic that will help you in your preparation for the State government recruitment jobs.
1. Geetha is 40 years old and Kiran is 60 years old. How many years ago was the ratio of their ages 3 : 5?
a) 10 years b) 20 years c) 37 years d) 5 years

Ans: a

---

Solution: Let x years ago the ratio of their age was 3 : 5

∴ According to the question

(40 – x) / 60 – x) = 3/5

=>; 200 – 5x = 180 – 3x
=>; 2x = 20

∴ x = 10 years

2. Four years ago, the ratio of the age of A and B was 2 : 3 and after four years it will become 5 : 7. Find their present age.
a) 32 years and 50 years b) 36 years and 52 years
c) 36 years and 40 years d) 32 years and 48 years
Ans: b
Solution: Four years ago, let the age of A and B be 2x and 3x years respectively.
According to the question,
(2x 4 4) / (3x 4 4) = 5/7
=>; (2x 8) / (3x 8) = 5/7

=>; 14x 56 = 15x 40
=>; x = 16
Present age of A = 2x 4
= 2 × 16 4 = 36 years
Present age of B
= 3x 4 = 3 × 16 4
= 52 years
3. The ratio of present age of two brothers is 1 : 2 and 5 years back the ratio was 1 : 3. What will be the ratio of their age after 5 years ?
a) 1 : 3 b) 3 : 4 c) 1 : 2 d) 3 : 5
Ans: d
Solution: Let the present age of two brothers be x and 2x years.
Now, (x – 5) / (2x – 5) = 1/3
=>; 3x – 15 = 2x – 5

=>; 3x – 2x = 15 – 5
=>; x= 10

∴ Their present age

= 10 and 20 years

After 5 years, their required ratio

= 15/25 = 3/5 = 3 : 5

4. The ratio of the ages of a father and his son 10 years hence will be 5 : 3, while 10 years ago, it was 3:1. The ratio of the age of the son to that of the father today is?

a) 5 : 6 b) 2 : 5 c) 1 : 2 d) 2 : 3

Ans: c

Solution: Let the age of father 10 years hence is 5x years,

Then age of son 10 years hence will be 3x years.

According to the question,

(5x – 10 – 10) / (3x – 10 – 10) = 3/1

(5x – 20) / (3x – 20) = 3/1
5x – 20 = 9x – 60

4x = 40 or x = 10

∴ Required ratio

= (3x – 10) : (5x – 10)

= 20 : 40 = 1 : 2

To be continued…

M. Venkat

Director
MVK Publications
Dilsukhnagar
7671002120