Three Statements S1, S2 and S3 are given below followed by a Question : S1 : C is younger than D, but older than A and B. S2 : D is the oldest. S3 : A is older than B. Question : Who among A, B, C and D is the youngest? Which one of the following is correct in respect of the above Statements and the Question?
- (a) S1 alone is sufficient to answer the Question.
- (b) S1 and S2 together are sufficient to answer the Question.
- (c) S2 and S3 together are sufficient to answer the Question.
- (d) S1 and S3 together are sufficient to answer the Question. ✓ UPSC's answer
Why the answer is (d)
• S1 states that C is younger than D but older than both A and B, establishing the partial order D > C > A and D > C > B.
• S3 states that A is older than B, which refines the relationship between A and B to A > B.
• Combining S1 and S3 yields the complete sequence: D > C > A > B.
• This sequence definitively identifies B as the youngest among the four.
• Therefore, S1 and S3 together are sufficient to answer the question, making option (d) correct.
Why the other options are wrong
- (a) S1 alone is sufficient to answer the Question.
- S1 alone only establishes that C is older than A and B, but does not determine the relative age between A and B.
- (b) S1 and S2 together are sufficient to answer the Question.
- S1 and S2 together still do not provide information to distinguish the relative ages of A and B.
- (c) S2 and S3 together are sufficient to answer the Question.
- S2 and S3 together do not provide any information about C's age relative to the others, making it impossible to determine the youngest.
Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2020, held on 4 October 2020. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.