Excluding the stoppages, the speed of a bus is 48 km/hr and including the stoppages the speed of the bus is 12 km/hr. For how many minutes does the bus stop per hour?  Choose the correct choice.
A) 45 min
B) 10 min
C) 12 min
D) 20 min
E) 18 min

Rationale: "speed of the bus without stoppage = 48 km / hr speed of the bus with stoppage = 12 km / hr difference in speed = 36 km / hr so , the time taken in the stoppages = time taken to cover 36 km = ( 36 / 48 ) hr = 3 / 4 hr = 45 min answer : a"
Answer: A