Question

A train travels some distance with a time speed of 30km/h and returns with a speed of 45km/h calculate the average speed of train

Answer 1

Let the train cover $d$ distance by traveling from one station to another. The time taken for its forward and backward journey is $\frac{d}{30}$ and $\frac{d}{40}$ respectively.

$\text{Average speed} = \frac{\text{Total distance}}{\text{Total time}}\\ =\frac{2d}{\frac{d}{30}+\frac{d}{45}}\\ =\frac{2}{\frac{1}{30}+\frac{1}{45}}\\ =\frac{2}{\frac{3+2}{90}}\\ =\frac{180}{5}\\ =36 kmph$