Aptitude - Problems on Trains - Discussion

D = S*T = 270+x = 500/9*9.

So x = 500-270 = 230.

Opposite direction: Adding.
Same Direction: Subtract.

Trains are move in opposite direction. But out of speed n distance one quantity is subtract but in the solution of this question both are added. Please explain I can't understand.

@Prasath.

5/18 means.

1 km = 1000 meter and 1hr = 3600 second.

Convert Kilometer per hour into Meter per second.

Divide the value of 1000/3600 its answer is 5/18.

Why there you take x+270/9?

How this 5/18 came? Can you solve this ?

Why we writing denominator 9 for x+270?

Use the formula, t = a+b/u+v, (train running opposite direction).

Where t = First train passes other train in time.

a+b = Length of train.

u = Speed of first train and v=speed of second train.

Then, 9 = 270+b/(120+80) km/hr.

<=> 270+b = 200 km/hr*9s = 500 m.

Now, b = 500-270 = 230 m.

Hi friends please help me,

How to identify relative speed and average speed and normal train problems?

If the two trains cross opposite directions both are cross each other. So we need calculate crossing speed of the two trains. So we must add two trains speeds respectively. We assumed train A cross train B in a particular amount of speed as same as Train B also cross Train A.

Here two respective speeds are happen then only the process completed in a particular Time. Or we assume Train A is stable that time train B only cross Train A that is Train A speed is zero this is the logic I hope now you can understand.