Question

A man is standing on a railway bridge which is 180m long.He finds that a train crosses the bridge in 20 seconds but himself in 8 seconds.Find the lengthof the train.

Answer 1

Let the length of the train be x metres.

Then, the train covers x metres in 8 seconds, and, (x+180) metres in 20 seconds.
$\Rightarrow \frac{x}{8}=\frac{x+180}{20}\Rightarrow 20x=8x+180\times 8\Rightarrow x=\frac{180\times 8}{12}\Rightarrow x=120$

Thus, the length of the train is 120 m.