UPSC Prelims 2004 · General Studies
Question 96: Basic Numeracy
Two cars X and Y start from two places A and B respectively which are 700 km apart at 9 a.m. Both the cars run at an average speed of 60 km/hr. Car X stops at 10 a.m. and again starts at 11 a.m. while the other car Y continues to run without stopping. When do the two cars cross each other?
AnswerThe answer is (b).
Both cars run at 60 km/h. By 11 a.m., Y has run 2 hours (120 km) while X has run only 1 hour (60 km), since it stopped from 10 to 11. They are 700 - 180 = 520 km apart. After 11 they close at 120 km/h, taking 520/120 = 4 hours 20 minutes, so they cross at 3:20 p.m.
Why each option is right or wrong
- (a) 2:40 p.m. is too early.
- (b) Correct: 11:00 + 4 h 20 min = 3:20 p.m.
- (c) 4:10 p.m. is too late.
- (d) 4:20 p.m. is too late.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2004, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.