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: Option B

Time from 7 a.m. to 4:15 p.m. = 9 hrs 15 min. = $$\frac{37}{4}$$ hrs
3 min. 5 sec. of this c;ocl = 3 min. of the correct clock
⇒ $$\frac{37}{720}$$ hrs. of this clock = $$\frac{1}{20}$$ hrs of the correct clock
⇒ $$\frac{37}{4}$$ hrs. of this clock = $$\left(\frac{1}{20}\times \frac{720}{37}\times \frac{37}{4}\right)$$     hrs. 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.