Excluding stoppages, the speed of a bus is 80 kmph and including stoppages, it is 60 kmph. For how many minutes does the bus stop per hour?  Choose the correct option.
A) 12 min
B) 20 min
C) 25 min
D) 30 min
E) 15 min

Rationale: "due to stoppages , it covers 20 km less . time taken to cover 20 km = ( 20 / 80 x 60 ) min = 15 min answer : e"
Answer: E