Excluding stoppages, the average speed of a bus is 60 km/hr and including stoppages, the average speed of the bus is 15 km/hr. For how many minutes does the bus stop per hour? Choose the correct choice from the following options.
A) 22  B) 88  C) 77  D) 20  E) 45

Rationale: "in 1 hr , the bus covers 60 km without stoppages and 15 km with stoppages . stoppage time = time take to travel ( 60 - 15 ) km i . e 45 km at 60 km / hr . stoppage time = 45 / 60 hrs = 45 min . answer : e"
Answer: E