Excluding stoppages, the average speed of a bus is 120 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) 40 min
In 1hr, the bus covers 120 km without stoppages and 40 km with stoppages.   Stoppage time = time take to travel (120 - 40) km i.e 80 km at 120 km/hr.   stoppage time = 80/120 hrs   = 40 min   Answer: 40 min
<result>E</result>
Excluding stoppages, the average speed of a bus is 120 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?