The minute and the hour hand of a watch meet every 65 minutes.
How much time does the watch lose or gain ?
(In reply to
Explanation For The Answer by K Sengupta)
At the outset, we know that:
The minute hand(mh) travels precisely 12 times faster than the hour hand(hh).
Therefore, the mh gains (12-1)=11 minute marks over hh for every 12 minute marks travelled by it.
So, mh gains 60 minute marks over hh when my has traveled (60*12)/11 =65+5/11 minutes over hh, when the two hand comes together.
But, by the problem, the two hands of this watch comes together every 65 minutes.
Accordingly, the referred to watch gains 5/11 minutes or, 5*60/11= 300/11 seconds over a normal watch in every 65 minutes.
Consequently, this watch gains (300/11)*(60/65)= 3600/143 ~ 25.1748 seconds in an hour over a normal watch.
Puzzle Solution: Method 2
