UPSC Prelims 2022 · CSAT

Question 25: Data Interpretation

Consider the Question and two Statements given below :

QuestionIs Z brother of X?
Statement–1X is a brother of Y and Y is a brother of Z.
Statement–2X, Y and Z are siblings.

Which one of the following is correct in respect of the Question and the Statements?

aStatement–1 alone is sufficient to answer the Question

bStatement–2 alone is sufficient to answer the Question

cBoth Statement–1 and Statement–2 are sufficient to answer the Question

dBoth Statement–1 and Statement–2 are not sufficient to answer the Question

AnswerUPSC’s answer is (d).

The question needs Z's gender relative to X. Statement 1 says X is a brother of Y and Y is a brother of Z; it gives nothing about whether Z is male or female, so Z may be a sister. Statement 2 says they are siblings, with no genders given. Combining them still leaves Z's gender open. Z could be a brother or a sister of X, so the statements are not sufficient.

Why each option is right or wrong

(a) Fails: Z's gender is not given.
(b) Fails: siblings could be of either gender.
(c) Fails: combining adds no information about Z's gender.
(d) Correct: Z may be a brother or a sister of X.

Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2022, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.