UPSC Prelims 2021 · CSAT
Question 25: Logical Reasoning and Mental Ability
Seven books P, Q, R, S, T, U and V are placed side by side. R, Q and T have blue covers and other books have red covers. Only S and U are new books and the rest are old. P, R and S are law reports; the rest are Gazetteers. Books of old Gazetteers with blue covers are
AnswerUPSC’s answer is (c).
Sort the seven books by each feature. Blue covers: R, Q, T. New: S, U, so old: P, Q, R, T, V. Law reports: P, R, S, so Gazetteers: Q, T, U, V. Old Gazetteers are the Gazetteers that are also old: Q, T and V. Of these, the ones with blue covers are Q and T. Remember: write a list for each condition and intersect them rather than reasoning in your head.
Why each option is right or wrong
- (a) R is blue and old but a law report, not a Gazetteer.
- (b) U is a Gazetteer but is new, and its cover is red.
- (c) Right: Q and T are old Gazetteers with blue covers.
- (d) T qualifies, but U is new with a red cover.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2021, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.