Question

A family consists of two grandparents, two 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 4years7
B.31 5years7
C.32 1years7
D.None of these

Answer 1

Average age of two grandparents=67 years
.·.Total age of 2 grandparents=(67×2) years=134 years

Average age of two parents=35 years
.·.Total Age of two parents=(35×2) years=70 years

Average age of three grandchildren=6 years
.·.Total age of three grandchildren=(6×3) years=18 years

.·. Total age of the Family members = (134+70+18) years=222 years
Total number of family members=(2+2+3) =7

.·.Average age of the whole family=
$\frac{Total age of family members}{No. of family members}$

=$\frac{222}{7}$ =31.7

So the correct option is B.31 5 years 7

Answer 2

Total age of grandparents =134 years.... Total age of parents = 70 years..... Total age of children =18 years... Total age of all of them =222years...... Average =222/7... =31.7...... So your answer is B...