Aptitude - Problems on Trains - Discussion

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!

Nothing tricky. We have to understand the concept of relative speed.

Keeping the faster train static we can consider the speed of slower train as (30+45) km/hr and as train has to pass the driver. Distance taken is 500m.

Speed=75km/hr=75*5/18m/sec.

Time taken=24sec.

Its tricky one. I made mistake in first attempt. Because I didn't read the Question well and assumed that it is asking 4 the time taken to cross each other.

Good one.

We should understand the Question well before attempting it.

Thank you sundar.

Very tricky Example...

Good one...

For the complete train to cross each other, it takes 48 sec.

To cross only the initial phase i.e. engine of first train facing the end of the second train. and engine of second train facing the end of the first train,it takes the half of the time to cross the complete train i.e. 48sec/2=24 sec.

Ans is correct. I did mistake at first time also.

It is a good one.

@All

Initially I was confused same like you. But, the given answer is correct.

We can assume the given question as:

A man running 45 km/hr opposite direction (against) to a train running 30 km/hr. Find the time taken by train to pass the man.

In the case of Man, Point, Pole.. the length will be considered as 0.

Note: In the given questions, IF it is mentioned like 'both train are running in SAME direction'.... then we can include the both train length (as Chandana said).

I hope this will help you a little bit. Have a nice day!

This is wrong. Try formula number 8 in formula section. We shoud use distance 1000.

Well done chandana at first I made same mistake by taking distance 1000m instead of 500.

I have got 15. Anyway, not bad.