Excluding stoppages, the speed of a train is 108 km/h and

Excluding stoppages, the speed of a train is 108 km/h and including stoppages, it is 90 km/h. For how many minute does the train stop per hour ?

Because of stoppages, train covers 18 km less per hour .
∴ Time taken to cover 18 km = 18/108 = 1/6 h = (1/6) x 60 = 10 min