UPSC Prelims 2008 · General Studies
Question 7: Basic Numeracy
In an examination, 70% of the students passed in the Paper I, and 60% of the students passed in the Paper II. 15% of the students failed in both the papers while 270 students passed in both the papers. What is the total number of students?
AnswerThe answer is (a).
Failing both is 15%, so 85% passed at least one paper. Using the union rule, the share who passed both is 70% + 60% - 85% = 45%. As 270 students passed both papers and that is 45% of the total, the total is 270 / 0.45 = 600 students.
Why each option is right or wrong
- (a) 45% of 600 is 270, which matches.
- (b) 45% of 580 is 261, not 270.
- (c) 45% of 560 is 252, not 270.
- (d) 45% of 540 is 243, not 270.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2008, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.