Correct Answer - Option 4 : 9
Given:
The average speed of a train without stoppages is 80 km/hr
The average speed of a train with stoppages is 68 km/hr
Formula Used:
Distance = Speed × Time
Calculation:
Without stoppages, in 1 hr train covers 80 km.
With stoppages, in 1 hr train covers 68 km.
Thus, the average speed of the train is reduced by 80 - 68 = 12 km
So the time taken to cover 12 km is now actually used up at stoppages.
⇒ Time is taken to cover 12 km = \(\frac{{12}}{{80}} × 60\) minutes = 9 minutes
∴ The train stops for 9 minutes in an hour on average.