Question

A train travelling at 36 kmph crosses a platform in 20 seconds and a man standing on the platform in 10 seconds. What is the length of the platform in metres?

• A. 240 metres
• B. 100 metres
• C. 200 metres
• D. 300 metres

Hint:

Crossing a man gives the train's own length; crossing the platform gives train length plus platform length.

Answer 1

The Correct Option is B

Step 1: Convert the speed to metres per second.
Speed of the train \(=36 \text{ kmph} = 36 \times \dfrac{5}{18} = 10\) m/s.

Step 2: Find the length of the train.
Crossing a man (a point object) takes 10 seconds, so length of train \(=\text{speed} \times \text{time} = 10 \times 10 = 100\) m.

Step 3: Find the combined length of train and platform.
Crossing the platform takes 20 seconds, so \(\text{length of train} + \text{length of platform} = 10 \times 20 = 200\) m.

Step 4: Solve for the platform length.
Length of platform \(=200-100=100\) m.

Step 5: Final Answer.
The platform is 100 metres long, so option B is correct.