1.  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:
A. 59(7/12) min. past 3
B. 4 p.m.
C. 58(7/11) min. past 3
D. 2(3/11) min. past 4

Answer: Option B

Explanation:

Time from 7 a.m. to 4.15 p.m.

= 9 hrs 15 min. = 37 hrs.
4

3 min. 5 sec. of this clock = 3 min. of the correct clock.

⇒ 37 hrs of this clock = 1 hrs.
720 20

⇒ 37 hrs of this clock = 1 x 720 x 37 .
4 20 37 4

      = 9 hrs of the correct clock.

∴ The correct time is 9 hrs after 7 a.m. i.e., 4 p.m.