Question

A watch which gains uniformly is 2 minutes low at noon on Monday and is 4 min. 48 sec fast at 2 p.m. on the following Monday. When was it correct?

Answer 1

The answer is 2 p.m. on Wednesday.

Solution:-
Time from 12 p.m. on Monday to 2 p.m. on the next Monday = 7 days 2 hours = 170 hours.

So,the watch gains 2 + 24/5 min. =  34/5 min. in 170 hrs.

Now,as 34/5 min. are gained in 170 hrs.

=>2 min. are gained in 170 x 5/34 x 2 hrs which is equal to 50 hrs

Hence,watch is correct 2 days 2 hrs. after 12 p.m. on Monday.This means that it will be correct by 2 p.m. on Wednesday.