A train traveling at 72 kmph crosses a platform in 30 seconds and a man standing on the platform in 20 seconds. What is the length of the platform in meters?
Choose the correct choice from the following:
A) 200 meters
B) 360 meters
C) 420 meters
D) 600 meters
E) can not be determined

Rationale: "speed of the train in metres / sec = 72000 / 3600 = 20 distance travelled by train to cross the platform = 30 * 20 = 600 = length of train + length of platform distance travelled by train to cross the man = 20 * 20 = 400 = length of train length of platform = 600 - 400 = 200 answer : a"
Answer: A