UPSC Prelims 2022 · CSAT
Question 40: Logical Reasoning and Mental Ability
Eight students A, B, C, D, E, F, G and H sit around a circular table, equidistant from each other, facing the centre of the table, not necessarily in the same order. B and D sit neither adjacent to C nor opposite to C. A sits in between E and D, and F sits in between B and H. Which one of the following is definitely correct?
AnswerUPSC’s answer is (d).
Place C at seat 0 of eight. B and D cannot sit at seats 1 or 7 (neighbours) or 4 (opposite), so each is at one of 2, 3, 5 or 6. A sits between D and E, and F between B and H, giving two blocks of three seats plus G alone. Checking every fit leaves six valid seatings (G at seat 1, 4 or 7). In them B is never between A and G, C is opposite G only when G is at seat 4, and E is opposite F in only two. No option holds in every seating.
Why each option is right or wrong
- (a) Fails: B sits next to F in every valid seating, never between A and G.
- (b) Fails: C is opposite G only when G is at seat 4.
- (c) Fails: E is opposite F in only two of the six valid seatings.
- (d) Correct: each of the other statements fails in some valid seating.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2022, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.