A train of length L is traveling at a constant velocity and passes a pole in t seconds. If the same train travelling at the same velocity passes a platform in 5t seconds, then what is the length of the platform?  Choose the correct choice from the following answers: A) l B) 2 l C) 3 l D) 4 l E) 5 l

Rationale: the train passes a pole in t seconds , so velocity v = l / t ( l + p ) / v = 5 t ( l + p ) / ( l / t ) = 5 t p = 4 l the answer is d .
Answer: D