A train 450 m long running at 126 kmph crosses a platform in 20 sec. What is the length of the platform?
Choose the correct option:
A) 271 B) 250 C) 350 D) 277 E) 232

Rationale: "length of the platform = 126 * 5 / 18 * 20 = 700 – 450 = 250 answer : b"
Answer: B