Multiple choice

A watch, which gains uniformly, is 3 minutes slow at 12 noon on Monday and is 5 minutes 36 seconds fast at 4 pm on the next Monday. At what time it was showing correct time?

  1. 12 am on Tuesday

  2. 12 pm on Wednesday

  3. 12 am on Thursday

  4. 12 pm on Thursday
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Total time = 7 days + 4 hours = 172 hours. Total gain = 3 min + 5 min 36 sec = 8.6 minutes = 516 seconds. Gain per hour = 516 / 172 = 3 seconds/hour. To correct 3 minutes (180 seconds), time = 180 / 3 = 60 hours. 60 hours = 2 days and 12 hours. Monday 12 noon + 2 days 12 hours = Thursday 12 am.

AI explanation

From 12 noon on Monday to 4 pm on the next Monday is 172 hours. The total relative shift in the watch is 3 minutes plus 5 minutes 36 seconds, which equals 8 minutes 36 seconds or 8.6 minutes. The watch shows the correct time when it erases its initial 3-minute deficit, requiring (3 / 8.6) of the total duration. This equals 60 hours after the start, so adding 60 hours to 12 noon on Monday brings the time to 12 am on Thursday.

Keep practicing — related questions