Excluding the stoppages, the speed of a bus is 48 km/hr and including the stoppages the speed of the bus is 24 km/hr. For how many minutes does the bus stop per hour?  Choices
A) 30 min  B) 10 min  C) 12 min  D) 20 min  E) 18 min

Rationale: "speed of the bus without stoppage = 48 km / hr speed of the bus with stoppage = 24 km / hr difference in speed = 24 km / hr so , the time taken in the stoppages = time taken to cover 24 km = ( 24 / 48 ) hr = 1 / 2 hr = 30 min answer : a"
Answer: A