Aptitude - Problems on Trains - Discussion

In problem, the two trains r running on parellel lines in the same direction, how can we take both of it as same length as x . can it be two trains of different lengths running parallel. Is this is assumption or fact.
Explain me

Why combined speed is compared to relative speed?

I think we can do like:

Relative speed is (46-36);

Length = (10*5/18)*36;
=100both
=50 each.

How it is possible? train length = x metres then distance =2x metres.

It's simple

We know the formula
u=(a+b)/x-y
let us take the lengh of the train is z(both trains len are same)
then
36=(z+z)/(46-36)*5/18
z=50m

How can we take 2X there?

How can we take 2X there?

Hi jayanth
read the problem carefully its given that the trains of equal length

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.

------------- Added by Author -----------------------------------
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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