A train traveling at 72 kmph crosses a platform in 31 seconds and a man standing on the platform in 18 seconds. What is the length of the platform in meters? Select.
A) 240 meters  B) 260 meters  C) 420 meters  D) 600 meters  E) can not be determined

Rationale: "speed of train = 72 * ( 5 / 18 ) = 20 m / s lets consider the man as a stationery point on the platform . crossing the point gives us the length of the train . lt = 20 * 18 = 360 m . crossing the platform gives us the length of trainlength of platform . l ( t + p ) = 20 * 31 = 620 m . so , length of platform = 620 - 360 = 260 m imo , answer b"
Answer: B