My husband`s watch gains 2 minutes every watch and my watch loses 1 minute for each hour. One day, we were late to marriage because the difference between the time in the two watches was 1 hr. and we looked at the slow watch. When did we last set our watches to the same time?
10 hrs.
14 hrs.
20 hrs.
18 hrs.
Explanation:
Suppose they had set their watches X hours ago.
Husband`s watch gains 2X/60 hour every hour while wife`s watch loses X/60 every hour.
Now as one watch gains and other loses the difference will be added
Hence (2X/60) + (X/69) = 1 (hour)
Thus, X = 20 hours.