# 8 years ago, the average age of Raj’s family of 5 members was 25 years. Two children having born (with age difference of 4 years), the present average

20 views
in Aptitude
closed
8 years ago, the average age of Raj’s family of 5 members was 25 years. Two children having born (with age difference of 4 years), the present average age of Raj’s family is the same. Find the present age of the youngest child.
1. 3 years
2. 4 years
3. 5 years
4. 6 years

by (53.1k points)
selected

Correct Answer - Option 1 : 3 years

Given

8 years ago, the average age of Raj’s family of 5 members = 25 years.

Age difference in two children’s = 4 years

Formula Used

Sum of the observation = Average × No. of observations

Calculation

Total age of 5 members, 8 years ago = 5 × 25 = 125 years

Total age of 5 members now = 125 + (8 × 5) = 125 + 40 = 165 years

Total age of 7 members now = 25 × 7 = 175 years

Sum of the ages of 2 children = 175 – 165 = 10 years

Let the age of the younger child be x years

Then age of elder child = (x + 4) years

So, x + x + 4 = 10

⇒ 2x = 10 – 4 = 6

⇒ x = 3 years

∴ The present age of youngest child is 3 years.