Excluding stoppages, the speed of a bus is 54 kmph and including stoppages, it is 45 kmph. For how many minutes does the bus stop per hour?  Answers.
A) 9  B) 10  C) 12  D) 20  E) 22

Rationale: "due to stoppages , it covers 9 km less . time taken to cover 9 km = ( 9 / 54 x 60 ) min = 10 min . answer : b"
Answer: B