X travels 6 km on a bicycle with average speeds of 5 km per hour, 10 km per hour and 4 km per hour during the first 1 km, the next 2 km and the remaining 3 km, respectively. Y travels the same distances with average speeds of 4 km per hour, 10 km per hour and 5 km per hour, respectively. How many minutes early will Y complete the journey if both X and Y start at the same time?
- (a) 3
- (b) 4
- (c) 5
- (d) 6 ✓ UPSC's answer
Why the answer is (d)
• X's time: 1/5 + 2/10 + 3/4 = 0·20 + 0·20 + 0·75 = 1·15 h.
• Y's time: 1/4 + 2/10 + 3/5 = 0·25 + 0·20 + 0·60 = 1·05 h.
• Y finishes 0·10 h = 6 minutes earlier: (d).
Why the other options are wrong
- (a) 3
- The time difference is 0·1 h = 6 min, not 3.
- (b) 4
- The time difference is 0·1 h = 6 min, not 4.
- (c) 5
- The time difference is 0·1 h = 6 min, not 5.
Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2026, held on 24 May 2026. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.