Discuss Forum
1. 5 years ago the ratio of father's age to son's age was 5 : 1 and 2 years later father's age will be 3 times his son's age. What is the ratio of their present age?
- A. 5 : 2
- B. 5 : 2
- C. 5 : 2
- D. 5 : 2
Answer: Option C
Explanation:
let, the present ages of the son and the father are a and b, respectively.
The age of the father 5 years ago was five times the age of his son.
a - 5 = 5(b - 5)
or, a – 5 = 5b - 25
∴ 5b - a = 20 - - - - - - - - - (1)
2 years hence, the father’s age will be thrice that of his son.
a + 2 = 3(b + 2)
or, a + 2 = 3b + 6
∴ a – 3b = 4 - - - - - - - - - - - - (2)
On adding (1) and (2), we get:
2b = 24
∴b = 12
Substituting b = 12 in equation (2), we ge, a = 40
Ratio of their present ages = a:b = 40:12 = 10:3
ans: 10:3
Post your comments here: