Correct Answer - Option 3 : 4 years

**Given**

Average age of 3 members of a family, 8 years ago = 39 years

**Concept used**

Average = Sum of all observation/ Number of observation

**Calculation**

Sum of the ages of 3 members, 8 years ago = 3 × 39

⇒ 117

Sum of the ages of 3 members, now = (3 × 39 + 8 × 3)

⇒ 117 + 24

⇒ 141

Sum of the ages of 5 members = 30 × 5

⇒ 150

Sum of the ages of children = 150 - 141

⇒ 9

According to question

let the age of younger child is x years and age of elder child is (x + 1) years

x + (x + 1) = 9

⇒ 2x = 9 - 1

⇒ 2x = 8

⇒ x = 4

**∴ Age of younger children is 4 years.**