In a family of 21 people, the average age is 14years. If the age of the grandfather is not counted, the average age drops to 12 years. What is the age of the grandfather?

A.
35 years 
B.
40 years 
C.
42 years 
D.
54 years
Correct Answer: Option C
Explanation
Total age of the whole family = 21 x 14 = 294
Total age without the grandfather = 21 x 12 = 252
Age of grandfather = 294 – 252
= 42 years