Excluding stoppages, the average speed of a bus is 80 km/hr and including stoppages, the average speed of the bus is 40 km/hr. For how many minutes does the bus stop per hour?  Select:	A) 15 min	B) 18 min	C) 16 min	D) 20 min	E) 30 min

Rationale: "in 1 hr , the bus covers 80 km without stoppages and 40 km with stoppages . stoppage time = time take to travel ( 80 - 40 ) km i . e 40 km at 80 km / hr . stoppage time = 40 / 80 hrs = 30 min answer : e"
Answer: E