Question

A wrist-watch loses 10 seconds every 8 hours. In how much time will it lose 15 sec?

Answer 1

It is given that
Time taken by a wrist watch to lose 10 sec = 8 hours
So the time taken by a wrist watch to lose 1 sec = 8/10 hours
Similarly the time taken by a wrist watch to lose 15 sec = 8/10 $\times$ 15 = 12 hours