2015 CSAT, all questions

UPSC Prelims 2015 · CSAT

Question 36: Basic Numeracy

Out of 130 students appearing in an examination, 62 failed in English, 52 failed in Mathematics, whereas 24 failed in both English and Mathematics. The number of students who passed finally is

a40
b50
c55
d60

AnswerUPSC’s answer is (a).

Count the students who failed in at least one subject: English 62 + Mathematics 52 − both 24 (counted twice) = 90. Those who passed all = 130 − 90 = 40. A common slip is to forget to subtract the overlap, which would give 62 + 52 = 114 failures and a wrong pass count of 16.

Why each option is right or wrong
  • (a) Right: 130 − 90 = 40.
  • (b) Wrong: 50 passed would mean 80 failed in at least one, but it is 90.
  • (c) Wrong: 55 passed would mean 75 failed, not 90.
  • (d) Wrong: 60 passed would mean 70 failed, not 90.

Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2015, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.