My watch is 1 minute slow at 1.00 pm on Tuesday and 2 minutes fast at 1.00 pm on Thursday. When did it show the correct time?
- 1.00 am on Wednesday
- 5.00 am on Wednesday
- 1.00 pm on Thursday
- 5.00 pm on Wednesday
- 5.00 pm on Thursday
The Usual Method
Between 1.00 pm on Tuesday and 1.00 pm on Thursday, there are 48 hours. Thus in 48 hours, the watch gains 1 + 2 = 3 minutes.
Hence, it gains 1 minute every hours.
Thus to show the correct time, it will have to gain 1 minute. Hence, we need to add 16 hours to 1.00 pm on Tuesday. 16 hours can be broken in to 12 + 4 hours.
12 Hours + 1.00 pm on Tuesday = 1.00 am on Wednesday.
4 Hours + 1.00 am on Wednesday = 5.00 am on Wednesday.
Estimated Time to arrive at the answer = 45 seconds.
Assume that the clock is 1 minute slow on Tuesday at 1.00 pm and 1 minute ahead on Thursday at 1.00 pm. Hence, the clock will show the correct time at 1.00 pm on Wednesday.
But the real gain of time is faster than assumed above. Thus the clock will show the correct time earlier than1.00 pm on Wednesday. The closest option is option ‘2’.
Estimated Time to arrive at the answer = 10 seconds.