1996 General Studies, all questions
UPSC Prelims 1996 · General Studies
Question 147: Basic Numeracy
The average of X1, X2 and X3 is 14. Twice the sum of X2 and X3 is 30. What is the value of X1?
a20
b27
c16
d12
AnswerThe answer is (b).
The average of the three numbers is 14, so X1 + X2 + X3 = 42. Twice the sum of X2 and X3 is 30, so X2 + X3 = 15. Hence X1 = 42 - 15 = 27. Remember: when an average is given, multiply back to get the total first, then subtract the known parts.
Why each option is right or wrong
- (a) X1 = 20 would make X2 + X3 = 22, not 15.
- (b) Right: X1 = 42 - 15 = 27.
- (c) X1 = 16 would make X2 + X3 = 26, not 15.
- (d) X1 = 12 would make X2 + X3 = 30, which is twice the given sum.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 1996, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.