Question

A long-distance train is scheduled to reach its destination in $19hours$. After $10hours$ of journey, due to disruption of rail traffic, the train has to be stationed for $1hour$. If the average speed of the train is $100km/hr$, at what speed should it travel to cover the distance in same amount of time?

Answer 1

Step $1$ : Compute the remaining distance.

Given: Total time$\left(t\right)=19hours$, average speed$=100km/hr$

Since, total distance$=$Speed$\times$Time

$\Rightarrow$ total distance$=19\times 100$

$\Rightarrow$ total distance$=1900km$\

Distance covered by train in $10$ hours is

Distance covered$=10\times 100$

$\Rightarrow$ Distance covered$=1000km$

Therefore, remaining distance$=1900-1000$

$\Rightarrow$ remaining distance$=900km$

Step $2$ : Compute the remaining time.

Given: the train has to be stationed for $1hour$.

Therefore, remaining time $=19-10-1$

remaining time $=8hours$

Step $3$ : Compute the required speed.

Since, the train should cover the distance in the same amount of time.

Therefore the speed of the train has to be changed.

So, required speed $=\frac{900}{8}$ [ Total distance $=$ Speed $\times$ Time ]

$\Rightarrow$ required speed$=112.5km/h$

Hence, in order to complete the journey at the same time the train should achieve a speed of $112.5km/hr$ .