2017 CSAT, all questions
UPSC Prelims 2017 · CSAT
Question 19: Logical Reasoning and Mental Ability
Consider the following : A + B means A is the son of B. A – B means A is the wife of B. What does the expression P + R – Q mean?
aQ is the son of P.
bQ is the wife of P.
cQ is the father of P.
dNone of the above
AnswerUPSC’s answer is (c).
A + B means A is B's son, and A - B means A is B's wife. In P + R - Q, the first part says P is the son of R, and the second says R is the wife of Q. So R is P's mother and Q is R's husband, which makes Q the father of P. Read such coding chains one link at a time, noting each person's sex from the symbol.
Why each option is right or wrong
- (a) Q is the husband of P's mother, not P's son.
- (b) Q is R's husband, so Q is male and cannot be a wife.
- (c) Correct: P is R's son and R is Q's wife, so Q is P's father.
- (d) The chain fixes the relation, so it is not none of the above.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2017, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.