Question

A 300 metre long train crosses a platform in 39 seconds while it crosses a post in 18 seconds. What is the length of the platform?

Answer 1

Answer:

speed of train = 300/18

therefore platform length= 300/18 * 39

=600metres

Answer 2

question:

A 300 metre long train crosses a platform in 39 seconds while it crosses a post in 18 seconds. What is the length of the platform?

answer:

speed =length of train /time taken to cross a post

=300/18=50/3 m/s

let the length of platform equal to x

speed = length of train + length of platform /time to cross platform

then 50/3 m/s = (300 + x )/30

$= > \frac{50m}{3s} = \frac{300 + x}{39} \\ = > 50 m\times 39 = 3s(300 + x) \\ = > 1950m = 900 + 3x \\ = > 3x = 1950 - 900 \\ = > x = \frac{1050}{3} \\ = > x = 350m$

so,the length of the platform

=350m