Question

A train passes two persons who are walking in the opposite direction of the train at the rates of 4 m/s and 10 m/s in 10 seconds and 8 seconds respectively. What is the speed of the train?

Options

• 15 m/s

• 20 m/s

• 40 m/s

• 10 m/s

Answer 1

20 m/s

Explanation:

Suppose speed of train is ‘s m/s’.

∴ (s + 4) × 10 = (s + 10) × 8

⇒ 10s + 40 = 8s + 80

⇒ 2s = 40

s = 20m/s