UPSC Prelims 2023 · CSAT
Question 77: Logical Reasoning and Mental Ability
Consider the following statements in respect of five candidates P, Q, R, S and T. Two statements are true and one statement is false. True Statement : One of P and Q was selected for the job. False Statement : At least one of R and S was selected for the job. True Statement : At most two of R, S and T were selected for the job. Which of the following conclusions can be drawn ?
- 1.At least four were selected for the job.
- 2.S was selected for the job.
Select the correct answer using the code given below :
AnswerUPSC’s answer is (d).
The false statement is 'at least one of R and S was selected', so neither R nor S was selected. Then only P, Q and T can be selected, which is at most three candidates, so 'at least four were selected' fails (conclusion 1). Since S was not selected, conclusion 2 also fails. The other two statements stay consistent with this. Neither conclusion can be drawn.
- 1. R and S are out, so at most P, Q and T, three candidates, can be selected.
- 2. The false statement means S was not selected.
How you could have got this
- If you were sure statement 1 is not correct, (a) and (c) go: each of them includes 1.
What you needed to know: R and S are out, so at most P, Q and T, three candidates, can be selected.
- Then, if you were sure statement 2 is not correct, (b) goes: it includes 2.
What you needed to know: The false statement means S was not selected.
Only (d) is left. This one needs every statement.
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: at most three (P, Q, T) can be selected.
- (b) Wrong: S was not selected.
- (c) Wrong: both conclusions fail.
- (d) Right: R and S are out, so neither conclusion holds.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2023, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.