A train passes a platform in 40 seconds. The same train passes a man standing on the platform in 20 seconds. If the speed of the train is 54 km/hr, The length of the platform is	Options:
A) 280 meter
B) 240 meter
C) 200 meter
D) 300 meter
E) none of these

Rationale: "explanation : speed of the train = 54 km / hr = ( 54 × 10 ) / 40 m / s = 15 m / s length of the train = speed × time taken to cross the man = 15 × 20 = 300 m let the length of the platform = l time taken to cross the platform = ( 300 + l ) / 15 = > ( 300 + l ) / 15 = 40 = > 300 + l = 15 × 40 = 600 = > l = 600 - 300 = 300 meter answer : option d"
Answer: D