UPSC Prelims 2017 · CSAT
Question 18: Logical Reasoning and Mental Ability
15 students failed in a class of 52. After removing the names of failed students, a merit order list has been prepared in which the position of Ramesh is 22nd from the top. What is his position from the bottom?
AnswerUPSC’s answer is (c).
Removing the 15 failed students leaves 52 - 15 = 37 in the merit list. Ramesh is 22nd from the top, so his place from the bottom is 37 - 22 + 1 = 16th. Always add 1, because Ramesh occupies a place himself: 15 students stand below him, which makes him 16th. Top rank plus bottom rank always equals the total plus one.
Why each option is right or wrong
- (a) 18th does not follow from 37 - 22 + 1.
- (b) 17th does not follow from 37 - 22 + 1.
- (c) Correct: 37 - 22 + 1 = 16.
- (d) 15th forgets to add 1: it counts only those below him, not him.
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.