Excluding stoppages, the average speed of a bus is 100 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?	Choose the correct choice from the following answers:
A) 15 min B) 18 min C) 16 min D) 20 min E) 36 min

Rationale: in 1 hr , the bus covers 100 km without stoppages and 40 km with stoppages . stoppage time = time take to travel ( 100 - 40 ) km i . e 60 km at 100 km / hr . stoppage time = 60 / 100 hrs = 36 min answer : e
Answer: E