Question

The average age of a family of five members is 16 years. The age of the youngest member of the family is 10.
What was the average age of the family at the time of birth of the youngest member?

• A. 11
• B. 11.5
• C. 7
• D. 7.5
• E. None of these

Answer 1

The correct option is D

7.5

Let the average of the four persons in the family apart from the youngest member be 'x'.
4x + 10 = 16 $\times$ 5
$⟹$ x = 17.5
$\therefore$ Average age 10 years ago = 7.5