Question

A family consists of grandparents, parents and three grandchildren. The average age of the grandparents is $67$ years, that of the parents is $35$ years and that of the grandchildren is $6$ years. What is the average age of the family?

• A. $28\frac{4}{7}$ years
• B. $31\frac{5}{7}$ years
• C. $32\frac{1}{7}$ years
• D. None of these

Answer 1

The correct option is B $31\frac{5}{7}$ years

Required average $=\frac{67\times 2+35\times 2+6\times 3}{2+2+3}$

$=\frac{134+70+18}{7}$

$=\frac{222}{7}$

$=31\frac{5}{7}years$