Question

A watch which gains 5 seconds in 3 minutes was set right at 7 a.m. In the afternoon of the same day, when the watch indicated quarter past 4 o'clock, the true time is:

Answer 1

The true time is 4 p.m

Time from 7 a.m. to 4.15 p.m. = 9 hrs 15 min. =37/4hrs.
3 min. 5 sec. of this clock = 3 min. of the correct clock.
37/720 hrs of this clock =1/20  x 720/37 x 37/4hrs of the correct clock.
= 9 hrs of the correct clock.
The correct time is 9 hrs after 7 a.m. i.e., 4 p.m.