2018 CSAT, all questions

UPSC Prelims 2018 · CSAT

Question 42: Basic Numeracy

19 boys turn out for playing hockey. Of these, 11 are wearing hockey shirts and 14 are wearing hockey pants. There are no boys without shirts and/or pants. What is the number of boys wearing full uniform?

a3
b5
c6
d8

AnswerUPSC’s answer is (c).

Every boy wears a shirt or pants or both. Use the union formula: total = shirts + pants - both. So 19 = 11 + 14 - both, which gives both = 25 - 19 = 6. Six boys wear the full uniform. Check: 5 wear shirts only, 8 wear pants only, 6 wear both, and 5 + 8 + 6 = 19.

Why each option is right or wrong
  • (a) With 3 in both, the total would be 22, not 19.
  • (b) With 5 in both, the total would be 20, not 19.
  • (c) Correct: 11 + 14 - 6 = 19.
  • (d) With 8 in both, the total would be 17, not 19.

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

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Source: UPSC, Civil Services (Preliminary) Examination 2018, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.