The distance between Delhi and Agra is 200km. A train travels the firs

1.	The distance between Delhi and Agra is 200km. A train travels the first 100 km at a speed of 50 km/h. How fast must the train travel the next 100 km so as to average 70 km/h for the whole journey?
Answer» Total distance = 200 km Average speed = 70 km/h Total time taken = total distance/average speed = 200/70 = 20/7 h First part of the journey, Distance = 100 km Speed = 50 km/h Time taken, t₁ = 100/50 = 2h Second part of the journey, Distance = 100 km Speed = x km/h Time taken, t₂ = 100/x h t₁ + t₂ = 20/7 x = 116.6 km/h

The distance between Delhi and Agra is 200km. A train travels the first 100 km at a speed of 50 km/h. How fast must the train travel the next 100 km so as to average 70 km/h for the whole journey?

Answer»

Total distance = 200 km

Average speed = 70 km/h

Total time taken = total distance/average speed = 200/70 = 20/7 h

First part of the journey,

Distance = 100 km

Speed = 50 km/h

Time taken, t₁ = 100/50 = 2h

Second part of the journey,

Distance = 100 km Speed = x km/h

Time taken, t₂ = 100/x h

t₁ + t₂ = 20/7

x = 116.6 km/h