Aptitude - Problems on Trains - Discussion

Can someone explain why they reversed the distance in the final calculation (i.e 125/6 to 6/125)?

What length we should consider if it is asked for faster train?

Hi, Chandana asked why don't we add the length of the train. Well this is a common doubt everybody gets .

Now you think, both are travelling in opposite direction.

Eg:

Train1 --------------> Fastest train

<---------------Train2. Slowest train

When this is the case the train1 and train2 travel with their respective speed. There will be no collision rigth because they travel in opposite direction. So we take only one length of the train that too the train we respect to .ie here we take the slower train which is 500 mts length.

Hope you got it. Have a nice day!

Why do we take 500 instead of 1000?

Please anyone explain me.

@All.

We use the length of the slower train because the problem is asking about the time it takes for the entire slower train to pass by the driver of the faster train. The calculation considers the time for the slower train to completely pass a single point (the driver), which depends on the train's full length.

Distance =speed * time,
500=45+30km/h*time,
500=75*5/18*time,
500=75*.277*time,
500=20.7*time,
Time=500/20.7=24s.

@All.

Answer is incorrect. It should be 48 instead of 24. If the given answer is correct then look at question number 9 the same question with different value then q. 9 is incorrect.

Here answer should be 48 explain it with given example let the speed of the first train be 4m/s and second be 1m/s and length of trains be 5/5 m then you should make number line and get two seconds so we must add 5+5 10m and divides by 5m/ (1+4).

@Raju.

In this problem, the relative speed is 75km/hr.
And to find the answer we have to convert the speed into m/s. So(75*5/18= 125/6m/s).
Hope that this will help you.

How 125÷6 came in this problem? Please explain.