A 300 metre long train crosses a platform in 39 seconds while it crosses a signal pole in 18 seconds. What is the length of the platform?

Given Data

• Train length = 300 m
• Time to pass a pole = 18 s
• Time to pass a platform = 39 s
• Required: platform length

Step 1: Find train speed from pole crossing
v = 300 ÷ 18 = 16.6667 m/s = 50/3 m/s

Step 2: Use platform crossing
39 = (300 + L) ÷ (50/3)300 + L = 39 × (50/3) = 650L = 650 − 300 = 350 m

Checks & Common Pitfalls

• Use only train length for pole to get speed.
• Add lengths for platform crossing.

Final Answer
The platform length is 350 m.