Question

A train crosses a 450 m long platform in 35 seconds and an 850 m long platform in 55 seconds. What is the length of the train?​

Answer 1

1 The Relative Speed of the train while crossing two bridges of the lengths of 430 m and 550 m in 30 and 36 seconds respectively.

2 The length of the train is common when crosses Both the Bridges and Only the Difference in The Times and The Lengths of the Bridges, Determines the Actual Speed of the train. Let's solve this.

3 Difference in Timings is 36 - 30 = 6 Seconds.

4 Difference in Length 550 - 430 = 120 meters.

5 It's clear that the train passes 120 meters in 6 seconds. And therefore The Speed in kmph is …

6 IN 6 seconds the distance is 120 Meters, and in 60 x 60 seconds... (120/6) x 3600 = 72 x 1000 meters ,or 72 kmph.

72 kmph answer.