Question

The average of the age of a father and his son is 30 yr. Ten years ago, their age were in ratio of 3 : 1. The age ratio of father and son after 10 years will be ________.
1. 3 : 1
2. 4 : 2
3. 5 : 3
4. 6 : 4

Answer 1

Correct Answer - Option 3 : 5 : 3

Calculation :

Given average age of both = 30

Sum of their age = 30 × 2 = 60 years.

Ten years ago, ratio = 3 : 1 and sum of age = 60 - 10 - 10 = 40,

Thus, their age were 30 years and 10 years respectively.

Current age 40 years and 20 years.

After 10 years, father age = 50, son age = 30,

Respective ratio = 5 : 3

In some years ago case, subtract the same year from the sum as many persons are given, not only once.