A train running at 90kmph takes 40 sec to pass a platform Next it takes 24 seconds to pass a man wal...........

Quantitative Aptitude (CDS) Problems on trains

A train running at 90kmph takes 40 sec to pass a platform. Next, it takes 24 seconds to pass a man walking at 9 kmph in the same direction in which the train is going. Find the length of the platform?

400meter

460meter

540meter

580meter

Explanation:

Let the length of the train be x metres and length of the platform by y metres
Speed of the train relative to man = (90-9) = 81kmph
= (81× 5/18)m/sec = 45/2 m/sec
In passing a man, the train covers its own length with relative speed.
Length of train = (Relative × time) = (45/2×24)m = 540m
Aso, speed of the train = (90× 5/18)m/sec = 25m/sec
(x+y)/25 = 40
x+y = 1000
y = 1000 - 540
=460meter