Question

A train crosses a 110 m long platform in 13.5 seconds and 205 m long platform in 18.25 seconds. What is the speed of the train?

Answer 1

,Let the length of the train is 'x' meters and the speed of the train is 's' m/s.

When it crosses the first platform,

(x + 110)/s = 13.5

⇒ x + 110 = 13.5s

⇒ x = 13.5s – 110 ----(1)

And when it crosses the second platform,

(x + 205)/s = 18.25

⇒ x + 205 = 18.25s

From equation (1), we get

13.5s – 110 + 205 = 18.25s

⇒ 4.75s = 95

⇒ s = 95/4.75

⇒ s = 20 m/s = 20 × 18/5 km/h = 72 km/h

∴ Speed of the train is 72 km/h

Answer 2

The speed of the train is 45.