Without any stoppage average speed of a train is 90 km/hr and with stoppage average speed reduces to 70 km/hr . Find the total time of stoppage in total 3 hours .

40 min

Distance = Speed × Time

Distance covered by train without any stoppage in 3 hours = 90 km/hr × 3 hr 

= 270 km

But it travelled = 70 km/hr × 3 hr  = 210 km 

Time taken to travel 210 km without stoppage = \(\frac{210}{90}\)

 = \(\frac{21}{9}\) hours

Difference in time = 3 - \(\frac{21}{9}\)= \(\frac{2}{3}\) hour = 40 min 

Total time of stoppage in 3 hours is 40 min .