Question

A train passes a 300 m long platform in 30 seconds and it crosses a signal in 12 seconds. The length of the train is _____

Answer 1

Answer:

Let length of train = L metres and speed = S m/s

Train covers (300 + L) metres in 30 seconds.

=> Speed of train = (300 + L)/30

Further, train covers L metres in 12 seconds.

=> Speed of train = L/12

Now, (300 + L)/30 = L/12

=> 3600 + 12L = 30L

L = 3600/18 = 200 m

Speed = 200/12 x 18/5 = 60 kmph

:-)