Question

A train covers a distance in 50 min, if it runs at a speed of 4 km/h.Calculate the speed at which the train must run to reduce the time of the journey to 40 min

Answer 1

Answer:

5 km/hr

Explanation:

Given:

speed = v = 4km/h

time = t = 50 min = $\frac{5}{6} hrs$

$distance=speed\times time$

substituting the given values,

distance=$4\times \frac{5}{6}$

distance=$\frac{20}{6} =\frac{10}{3}$ kilometres

To find:

• speed at which train must run to reduce the time of journey to 40 min

40 min = $\frac{2}{3} hr$

distance will be same and constant=$\frac{10}{3} km$

substituting,

$\frac{10}{3}=speed\times \frac{2}{3}$

speed = $\frac{10}{3} \times \frac{3}{2}$

speed = $\frac{10}{2} km/h$

speed = 5km/h

The speed should be 5 kilometres per hour