UPSC Prelims 2001 · General Studies
Question 140: Basic Numeracy
A worker reaches his factory 3 minutes late if his speed from his house to the factory is 5 km/hr. If he walks at a speed of 6 km/hr, then he reaches the factory 7 minutes early. The distance of the factory from his house is
AnswerThe answer is (b).
Let the distance be d km. At 5 km/h he takes d/5 hours and is 3 minutes late; at 6 km/h he takes d/6 hours and is 7 minutes early. The difference in times is 10 minutes, or 1/6 hour. So d/5 - d/6 = 1/6, which gives d/30 = 1/6 and d = 5 km. Check: 60 minutes at 5 km/h, 50 minutes at 6 km/h.
Why each option is right or wrong
- (a) 4 km does not give a 10 minute difference (48 and 40 minutes).
- (b) Right: 5 km.
- (c) 6 km gives a 12 minute difference.
- (d) 7 km gives a 14 minute difference.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2001, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.