1. 

The average age of P, Q, R and S is 30 years. How old is R ?

I. The sum of ages of P and R is 60 years.

II. S is 10 years younger than R.

A. I alone sufficient while II alone not sufficient to answer
B. II alone sufficient while I alone not sufficient to answer
C. Either I or II alone sufficient to answer
D. Both I and II are not sufficient to answer
E. Both I and II are necessary to answer

Answer: Option D

Explanation:

P + Q + R + S = (30 x 4)  

   P + Q + R + S = 120 .... (i)

I. P + R = 60 .... (ii)

II. S = (R - 10) .... (iii)

From (i), (ii) and (iii), we cannot find R.

Correct answer is (D)