Aptitude - Problems on Trains - Discussion

A train travels in one houe=20 km.

Now at 8 o'clock distance between tow trains = 90 km.
It is relavent to these two trains speed =20+25km/h = 45km/h.
Now time = distance/speed.
= 90/45 = 2h.

Hence trains meet after 2hours that is 8+2 = 10 a.m.

Thank you @Manish Dabhi.

Thank you very much @Yuvaraj.

Platform A ____110km____ Platform B.


Difference between train A and train B is =1hr.
Relative speed of both the trains are = (20kmph+25kmph)= 45kmph.
Now think as if you are the boss (what if you can make both the trains depart at 8 AM how much easy it would have become).
So, the train A is moving at 20km in 1 hour at 7 AM it means it already has completed 20kms by 8 AM from the given distance of 110 km = so (110-20=90 km) left for train A.

And being a boss you now calculate from 8AM for both the trains.
Assume,
If they both depart at 8 AM
Train A now have to go 90 km more
Train B have to go 110 km
So we will calculate
D=S*T ( distance still left = relative speed *time
90=45*time
90/45=2.

2 hours from the time which we shifted like a boss 8 AM so add 2 hours more after 8.
Its 10 AM.

A_________________110KM______________________B.

7.00 AM. 8.00 AM.
20 KMH. 25 KMh.
2nd train after 1 hour.

So 1st train gone to 20 km.
Because totally 110-20 = 90 km.
Now 20 kmh+25 kmh = 45 kmh.
90/45 = 2 hours.
Now we count 8.00 am+ 2 hours = 10.00 AM.

Here
V1 =20 km/hr.
V2 = 25km/hr.
Time of meet they
= 110-20/20 + 25.
= 2hr.
Then 8+2 = 10am.

This is based on relative speed.

If they are in opposite directions just add their speeds if they are in same directions subtract their speeds.

How to solve if they move in the same direction?

How this 3 hr comes?

The difference of speeds of two trains P & Q is 20km/hr. Train P & Q start from points A & B & move towards each other. If the trains meet each other after 2 hr of the journey. What is the speed of the faster train?

Please answer it.