Question

A train passes a 110 m long platform in 40 s and a boy standing on the platform in 30 s. The length of the train is

Options

• 100 m

• 110 m

• 200 m

• 330 m

Answer 1

330 m

Explanation:
Let the length of train = x m
∴ Speed of train while crossing a platform = `(110+"x")/40`m/s

and speed of train while crossing a boy = `"x"/30`

∴ `"x"/30=(110+"x")/40`

⇒ 4x = 330 +3x 

∴ x = 330 m