Question

A train of length 'x' m can cross a platform of length 'y' m in 25 seconds. The same train can cross a bridge thrice the length of the platform in 50 seconds, then find the ratio of the length of the platform to the length of the train.
1. 1 : 1 
2. 1 : 2
3. 1 : 3
4. 1 : 4

Answer 1

Correct Answer - Option 1 : 1 : 1 

Given :

A train of length 'x' m can cross a platform of length 'y' m in 25 seconds.

The same train can cross a bridge thrice the length of the platform in 50 seconds.

Formula used :

Time = Distance/Speed 

Calculations :

Let the speed of train be 'S' km/h

Let the length of train be 'x' m

Let the length of platform be 'y' m 

Length of bridge = 3 × platform length = '3y' m 

According to the question 

25 = (x + y)/S     ....(1) (time = (distance of bridge + length of train)/speed of train)

50 = (x + 3y)/S     ....(2) 

Now solving equations 1 and 2 we get

(x + y)/(x + 3y) = 1/2 

x : y = 1 : 1 

∴ The ratio of the length of the train and platform is 1 : 1