Question

On 200km track a train covers a distance of 50km at a speed of 25km/h. At what speed the train shouldtravel the next 150km so as to have the average speed of the train as 40km/h

Answer 1

Given:-

→Total length of the track = 200km

→Speed with which the train covers first 50km = 25km/h

→Average speed of the train = 40km/h

To find:-

→Speed with which,the train should travel the next 150km

Solution:-

Let the required speed of the train be v₂ and time taken by the train to cover first 50km be t₁ and for the next 150km be t₂

We know that:-

=>Time = Distance/Speed

=>t₁ = 50/25

=>t₁ = 2h

=>t₂ = 150/v₂

Now,we know that:-

Average Speed:-

Total distance covered/Total time taken

=>200/(2+150/v₂) = 40

=>200/(2v₂+150/v₂) = 40

=>200v₂ = 40(2v₂+150)

=>200v₂ = 80v₂+6000

=>6000 = 200v₂ - 80v₂

=>6000 = 120v₂

=>v₂ = 6000/120

=>v₂ = 50km/h

Thus,the train should cover next 150km with a speed of 50km/h.