Aptitude - Problems on Trains - Discussion

How we assume x=3 then how we get both meeting time at 10 please explain clearly to me.

Simple solution no formula, no concepts just common sense.

Let us consider first train it's speed is 20 km/hr.

So it covers 20 kms in 1 hour.

Starting from 7 am 1st train second train from 8 am to 9 am.

At 8 am it covers 20 km at 9 am it covers 25 km. 9 am it covers 40 km 10 am it covers 50 km.

10 am === 60 km.

So at 10 am total distance covered by two trains is 60+50=110 km.

Which is the actual distance of separation between two train hence they meet each other so simple.

Let 't' b the time in hrs the two trains meet. Then distance traveled by 1st train is 20t and distance.

Traveled by 2nd train is 25 (t-1). Because 2nd train run after 1hr of 1st train.

Total distance = 110 km = 20t+25(t-1).

Solving we get t = 3hr. 7 a.m.+3hr = 10 a.m.

@Chai.

Answer : 2.15 pm. Is this correct?

@Chai.

Sorry I will be confused. I got two answers by solving two different methods.

I got 2.15 pm and also I got 4.15 pm.

One train will cover 20 km in one hour.

Now the distance remaining is 90 km.

So time take is equal to 90/20+25 = 2 hours means will meet 2 hours after 8 am i.e. 10 am.

A and B are two stations 390 km a part. A train start from A at 10 AM and travels towards B at 65 kmph. Another train start from B at 11 AM and travels towards A at 35 kmph. At what time do they meet? Solve this problem.

How 20x + 25(x-1) = 110?

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.

Hai @Poojitha.

x is the time taken, 20 is speed.

So Speed*Time = Distance.

For first train it is 20x. And as the second train started 1 hr later.

The time will be x-1. And distance = 25(x-1).

Since both the trains are yet to cover 110 km.

And travelling in opposite directions to meet each other and we have to calculate the meeting point of time. We have to add them. So,

It is 20x+25(x-1) = 110.

Hope it is clear now.