Aptitude - Problems on Trains - Discussion

We can slove like this
relative speed =10km/hr
distance=speed*time
=(10*5/18)*36
=100m
distance=sum of length of train
since both r equal length
length of each =50m

The correct answer is 100 mts. We can take the length of only one train as answer as both the trains started at the same point and time. The faster train has just to cover its length only to cross the slower train. The formula is:

((46-36)kmph*5/18)*36=50/18*36=100mts.

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This answer is wrong. We have to read the question very carefully, there is no information like "started at the same time and same point".
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Hello Friends,
If 2 trains of length a and b moving in same direction at u,v.Then the time taken by the faster train to cross the slower train is =(a+b)/(u-v)sec.
So here,Time=36sec and u+v=25/9m/sec
Then the formula is,36=(a+b)/(925/9)
a+b=100
Now we get a=50 and b=50
I think ur doubt is clear now

Why we are taking 2x?

Because both trains are of equal length, mentioned in question. So lets take length=x, then to cross another train of same length i.e. x. First train have to cover distance of x+x.

Thats why he has taken 2x.

@appu. I understand your way of explaining. Its clear my doubts. Thanks.

You have taken 2x/36.

Is it the speed of the slower train or the time taken to overtake?

Please explain how to take distance covered=2x meters.

Distance=sum of length of two trains.

How it is please anyone explain.

Why did take the differences of speed?