A train travelling at 48 kmph completely crosses another train having half its length and travelling in opposite direction at 42 kmph, in 12 seconds. It also passes a railway platform in 45 seconds. The length of the platform is
Choose the correct answer.
A) 400 m  B) 450 m  C) 560 m  D) 600 m  E) 700 m
Explanation:   Let the length of the first train be x metres.   Then, the length of the second train is(x/2)metres.   Relative speed = (48 + 42) kmph =(90x5/18)m/sec = 25 m/sec.   [x + (x/2)]/25	= 12 or	3x/2	= 300 or x = 200.   Length of first train = 200 m.   Let the length of platform be y metres.   Speed of the first train =(48 x5/18)m/sec =	40	/3m/sec.   (200 + y) x	3/40=45   600 + 3y = 1800   y = 400 m.   400 mNSWER IS 400 m
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A train travelling at 48 kmph completely crosses another train having half its length and travelling in opposite direction at 42 kmph, in 12 seconds. It also passes a railway platform in 45 seconds. The length of the platform is