A train traveling at 108 kmph crosses a platform in 30 seconds and a man standing on the platform in 12 seconds. What is the length of the platform in meters?
Choose the correct answer:	A) 240 meters	B) 360 meters	C) 420 meters	D) 600 meters	E) Cannot be determined
Answer   Distance covered by the train when crossing a man and when crossing a platform   When a train crosses a man standing on a platform, the distance covered by the train is equal to the length of the train.   However, when the same train crosses a platform, the distance covered by the train is equal to the length of the train plus the length of the platform.   The extra time that the train takes when crossing the platform is on account of the extra distance that it has to cover. i.e., length of the platform.   Compute length of platform   Length of the platform = speed of train * extra time taken to cross the platform.   Length of platform = 108 kmph * 12 seconds   Convert 108 kmph into m/sec   1 kmph = 5/18 m/s (This can be easily derived. But if you can remember this conversion, it saves a good 30 seconds).   ∴ 108 kmph = 5/18∗108 = 30 m/sec   Therefore, length of the platform = 30 m/s * 12 sec = 360 meters.   Choice 360 meters
<result>B</result>
A train traveling at 108 kmph crosses a platform in 30 seconds and a man standing on the platform in 12 seconds. What is the length of the platform in meters?