Excluding stoppages, the average speed of a bus is 60 km/hr and including stoppages, the average speed of the bus is 45 km/hr. For how many minutes does the bus stop per hour?	Answers:
A) 15
B) 88
C) 77
D) 20
E) 99

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