Excluding stoppages, the average speed of a bus is 75 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?
Pick
A) 15 min	B) 18 min	C) 16 min	D) 20 min	E) 28 min

Rationale: "in 1 hr , the bus covers 75 km without stoppages and 40 km with stoppages . stoppage time = time take to travel ( 75 - 40 ) km i . e 35 km at 75 km / hr . stoppage time = 35 / 75 hrs = 28 min answer : e"
Answer: E