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.

2 station A and B are 110km apart.
1 train start from A at 7 am towards B at 20 kmph 110-20 = 90.

Next one start from B at 8 a.m towards A at 25kmph.
20+25 =45.

Now 90/45 = 2hrs.
.`. 8+2 = 10 a.m.

Your values for the distance travelled by each train are mathematically correct based on their speeds and times.

But from 10:00 a.m. onward, your reasoning ignores that the trains would have already met at 10 a.m.

Because their combined distance = 110 km, which is the total distance between A and B.

So, continuing to add distances after the meeting point doesn't make logical sense in the context of this problem.

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.

Thank you very much @Yuvaraj.

Thank you @Manish Dabhi.

How we are obtained the 10 ?

Please explain it.

@Chai.

I got 2.25 is it correct or not?

Why it's taken x-1 but not x+1 because train 2 starts 1 hr later?

Here x=3 is answer how to convert into am/pm some other problem.