UPSC Prelims 2017 · CSAT
Question 9: Logical Reasoning and Mental Ability
No supporters of ‘party X’, who knew Z and supported his campaign strategy, agreed for the alliance with ‘party Y’; but some of them had friends in ‘party Y’. With reference to the above information, which one among the following statements must be true?
AnswerUPSC’s answer is (b).
Call the supporters of X who knew Z and backed his strategy group G. None of G agreed to the alliance, but some of G have friends in Y. G is therefore not empty, and at least one Y supporter is a friend of an X supporter: (b) must be true. A non-empty G also rules out (c) and (d). Nothing is said about Y supporters' own stand on the alliance, so (a) is unsupported.
Why each option is right or wrong
- (a) Only X supporters in G are described; nothing is said about Y supporters' stand on the alliance.
- (b) Correct: some members of G have friends in Y, so at least one Y supporter is a friend of an X supporter.
- (c) G is non-empty and its members do support Z's strategy, so this is false.
- (d) G's members knew Z, and G is not empty, so some X supporters did know Z.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2017, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.