Question

A watch showed five past five on Wednesday evening when the correct time was 5: 00 p.m. It loses uniformly and is 5 minutes slow after 2 days at 7: 00 p.m. When did the watch show the correct time?
(a)Thursday 6: 00 am
(b)Thursday 6: 00 pm
(c)Thursday 6: 30 pm
(d)Thursday 5: 00 am
(e)None of these

Answer 1

Hint: The watch is 5 minutes slow after 2 day i.e. Friday 7:00 pm. Thus find the time difference from Wednesday 5:00 pm to Friday 7: 00pm. The correct time will be the mid- point of these 2 times.

Complete step-by-step answer:
It is said that a watch shows five past on Wednesday evening which means that the clock was 5 minutes past on Wednesday when the correct time was 5: 00 pm.
Now it is said that the watch is 5 minutes slow after 2 days at 7: 00 pm which is a Friday. Thus we can say that the correct time would be the mid – point of these 2 times.
Now we need to calculate the time difference from Wednesday 5: 00 pm and Friday 7: 00 pm.
Thus the time from Wednesday 5: 00 pm to Thursday 5: 00 pm is 24 hrs. The time from Thursday 5: 00 pm to Friday 5: 00 pm is 24 hrs. The time difference between Friday 5: 00 pm to 7: 00 pm is 2 hrs.
Thus the total time difference between Wednesday 5: 00 pm to Friday 7: 00 pm is equal to 24 + 24 + 2 = 50 hrs.
Thus taking the half of the time difference we got = \[\dfrac{50}{2}=25\]hrs.
Hence the right time will be 25 hours past 5: 00 pm Wednesday.
We said that Wednesday 5: 00 pm to Thursday 5: 00 pm is 24 hours. So adding 1 hr, along to it, will be Thursday 6: 00 pm.
Thus the right time is Thursday 6: 00 pm.
Thus the watch showed the correct time at Thursday 6: 00 pm.
\[\therefore \] Option (b) is the correct answer.

Note: We should know the basic time difference that a day is 24 hrs. Similarly, we should know that the time difference between 5: 00 pm on Wednesday and Thursday is 24 hrs. Similarly, calculate the time difference without error.