A 180m long train is running at 72 kmph.If it crossed the platform in 20 sec.then find the platform length? Choose the correct choice:
A) 220 m  B) 110 m  C) 230 m  D) 100 m  E) 90 m

Rationale: length = speed * time length = 72 km / hr * time length = [ 72 * ( 5 / 18 ) ] * 20 { ( ie ) ( x ) km / hr ) } = x * ( 5 / 18 ) = 20 * 20 length = 400 m length of platform = length - length of the train length of platform = 400 - 180 length of platform = 220 m option a
Answer: A