Question

A train crosses a 200 m tall lamp post in 10 seconds and a 300 m long platform in 20 seconds. Find the speed of the train in m/s.

• A. 10 m/s
• B. 15 m/s
• C. 25 m/s
• D. 30 m/s

Answer 1

The correct option is D 30 m/s

In the first case, the height of the lamp post is immaterial.

Also, the train crosses the lamp post in 10 seconds and then it crosses its own length in 10 seconds.

In that extra (20 – 10) = 10 seconds in the next case, the train crosses the 300 m long platform.

So, the speed of the train = 300/10 = 30 m/s

Hence, option (D) is the correct answer.