A train crosses a post in 10 s when it is travelling at 72 km/h. Find the length of the train (in m).

A train crosses a pole in 12 s, when it is traveling at 54 km/h. Find the length of the train.

A train crosses a stationary pole in 20 s when it is travelling at 54 km/h. Find the length of the train (in m).

A train crosses a platform in 30 seconds travelling with a speed of 60 km/h. If the length of the train be 200 metres, then the length (in metres) of the platform is