Average - General Aptitude

Each of the questions given below consists of a statement and / or a question and two statements numbered I and II given below it. You have to decide whether the data provided in the statement(s) is / are sufficient to answer the given question. Read the both statements and
  • Give answer (A) if the data in Statement I alone are sufficient to answer the question, while the data in Statement II alone are not sufficient to answer the question.
  • Give answer (B) if the data in Statement II alone are sufficient to answer the question, while the data in Statement I alone are not sufficient to answer the question.
  • Give answer (C) if the data either in Statement I or in Statement II alone are sufficient to answer the question.
  • Give answer (D) if the data even in both Statements I and II together are not sufficient to answer the question.
  • Give answer(E) if the data in both Statements I and II together are necessary to answer the question.
Q1:

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

ANS:D - Both I and II are not sufficient to answer

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)