UPSC Prelims 2019·CSAT·Logical Reasoning·Clocks and Calendars

A wall clock moves 10 minutes fast in every 24 hours. The clock was set right to show the correct time at 8:00 a.m. on Monday. When the clock shows the time 6:00 p.m. on Wednesday, what is the correct time ?

Dalvoy logo
Reviewed by Dalvoy
UPSC Civil Services preparation
Last updated 23 May 2026, 3:31 pm IST
  1. A5:36 p.mCorrect
  2. B5:30 p.m
  3. C5:24 p.m
  4. D5:18 p.m.

Explanation

To solve this, we first calculate the total time elapsed on the fast clock. From Monday 8:00 a.m. to Wednesday 8:00 a.m. is 48 hours. From Wednesday 8:00 a.m. to Wednesday 6:00 p.m. is 10 hours. Total elapsed time on the fast clock is 58 hours. The clock gains 10 minutes every 24 hours. This means for every 24 hours of true time, the clock shows 24 hours and 10 minutes. Converting this to a ratio, 24 hours of true time equals 1450 minutes on the fast clock, while 24 hours of true time is actually 1440 minutes. Ratio of True Time to Fast Clock Time is 1440 divided by 1450, which simplifies to 144 divided by 145. To find the actual time passed, multiply the fast clock duration of 58 hours by this ratio: 58 multiplied by 144 divided by 145. This equals 57.6 hours. Convert 0.6 hours into minutes: 0.6 multiplied by 60 equals 36 minutes. So, the true time passed is 57 hours and 36 minutes. Adding 57 hours and 36 minutes to Monday 8:00 a.m. results in Wednesday at 5:36 p.m. Therefore, option A is correct.
Logical Reasoning: A wall clock moves 10 minutes fast in every 24 hours. The clock was set right to show the correct time at 8:00 a.m. on M

Related questions

More UPSC Prelims practice from the same subject and topic.