Question

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
A.400 m
B.450 m
C. 560 m
D.600 m

Answer 1

Answer: Option A

Explanation:

Let the length of the first train be x metres.

Then, the length of the second train is xmetres.2

Relative speed = (48 + 42) kmph =90 x5m/sec = 25 m/sec.18

[x + (x/2)]= 12 or3x= 300     or     x = 200.252

 Length of first train = 200 m.

Let the length of platform be y metres.

Speed of the first train =48 x5m/sec =40m/sec.183

 (200 + y) x3= 4540

 600 + 3y = 1800

 y = 400 m.