UPSC Prelims 2026 · CSAT
Question 33: Logical Reasoning and Mental Ability
P, Q, R, S and T are ranked 1 to 5 (not necessarily in that order). The rank of P is 4, the rank of Q is not 5, the rank of R is 1, the rank of S is not 2, the rank of T is not 3. Then which of the following is/are correct?
- IIf the rank of S is 3, then that of T is 2.
- IIIf the rank of Q is 3, then that of T is 5.
Select the answer using the code given below.
AnswerUPSC’s answer is (d).
P = 4 and R = 1, leaving ranks 2, 3 and 5 for Q, S and T. Q is not 5, so Q is 2 or 3; S is not 2, so S is 3 or 5; T is not 3, so T is 2 or 5. If Q = 2, then T = 5 and S = 3. If Q = 3, then S = 5 and T = 2. These are the only two arrangements. In the first, S = 3 but T = 5, so I fails; in the second, Q = 3 but T = 2, so II fails.
- I. S = 3 occurs only with Q = 2 and T = 5.
- II. Q = 3 occurs only with S = 5 and T = 2.
How you could have got this
- If you were sure statement I is not correct, (a) and (c) go: each of them includes I.
What you needed to know: S = 3 occurs only with Q = 2 and T = 5.
- Then, if you were sure statement II is not correct, (b) goes: it includes II.
What you needed to know: Q = 3 occurs only with S = 5 and T = 2.
Only (d) is left. This one needs every statement.
This follows UPSC’s provisional key; the final key could change it.
Which options go is worked out from UPSC’s key and the options, not by a model.
Why each option is right or wrong
- (a) Wrong: when S = 3, T is 5, not 2.
- (b) Wrong: when Q = 3, T is 2, not 5.
- (c) Wrong: both statements fail.
- (d) Right: both fail in the only two valid arrangements.
Only the provisional key (27 May 2026) was found; the final key replaces it when found.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2026, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.