UPSC Prelims 2022 · CSAT
Question 6: Logical Reasoning and Mental Ability
Two friends X and Y start running and they run together for 50 m in the same direction and reach a point. X turns right and runs 60 m, while Y turns left and runs 40 m. Then X turns left and runs 50 m and stops, while Y turns right and runs 50 m and then stops. How far are the two friends from each other now?
AnswerUPSC’s answer is (a).
Take the shared 50 m as north. X turns right (east) for 60 m, then left (north) for 50 m, ending 60 m east of the line and 50 m further north. Y turns left (west) for 40 m, then right (north) for 50 m, ending 40 m west of the line and also 50 m further north. Both moved the same distance north, so they are level and the gap is 60 + 40 = 100 m. Sketch the path: when the turns mirror each other, only the sideways offsets add.
Why each option is right or wrong
- (a) Correct: 60 m east plus 40 m west, with equal northward travel, gives 100 m.
- (b) 90 m is not produced by any combination of the legs.
- (c) 60 m counts only X's sideways run.
- (d) 50 m is the last northward leg, which both friends ran equally and which adds nothing to the gap.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2022, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.