A 250 m long train is running at a speed of 55 Km/hr. It crossed a platform of length 520 m in ?	Select the correct option
A) 41.1 sec
B) 20.2 sec
C) 31.8 sec
D) 50.4 sec
E) none of the above

Rationale: "speed = 55 km / hr ( to convert km / hr in to m / s ) = 55 x 5 / 18 m / s distance = 250 m + 520 m ( if questions is about train crossing a post you need to consider only the length of train , ) = 770 m time = distance / speed = 770 x 18 / ( 5 x 55 ) = 50.4 sec ans is : d"
Answer: D