Time and Distance-2

Excluding stoppages, the speed of the bus is 54kmph & including stoppages, it is 45kmph. For how many minutes does the bus stop per hour?
(A) 9 (B) 10 (C) 12 (D) 20
Answer: B

Description:
Due to stoppages, it covers 9 km less.
Time taken to cover 9 km=[ (9/54)*60] min
==>10 Minutes