A goods train runs at the speed of 72 kmph and crosses a 250 m long platform in 30 seconds. What is the length of the goods train? Choose the correct option.
A) 230 m  B) 350 m  C) 260 m  D) 270 m  E) none of these

Rationale: "explanation : speed = [ 72 x ( 5 / 18 ) ] m / sec = 20 m / sec . time = 30 sec . let the length of the train be x metres . then , [ ( x + 250 ) / 30 ] = 20 = > x + 250 = 600 = > x = 350 . answer : b"
Answer: B