2013 CSAT, all questions
UPSC Prelims 2013 · CSAT
Question 66: Basic Numeracy
A person can walk a certain distance and drive back in six hours. He can also walk both ways in 10 hours. How much time will he take to drive both ways ?
aTwo hours
bTwo and a half hours
cFive and a half hours
dFour hours
AnswerUPSC’s answer is (a).
Let walking one way take w hours and driving one way take d hours. Walking one way and driving back takes w + d = 6. Walking both ways takes 2w = 10, so w = 5 and d = 1. Driving both ways therefore takes 2d = 2 hours. Two equations, two unknowns, then double the driving time.
Why each option is right or wrong
- (a) Right. d = 1, so both ways take 2 hours.
- (b) Wrong. 2.5 hours would mean d = 1.25 and w + d = 6.25.
- (c) Wrong. 5.5 hours would mean d = 2.75 and w + d = 7.75.
- (d) Wrong. 4 hours would mean d = 2 and w + d = 7.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2013, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.