Aptitude - Problems on Trains - Discussion

Easy way:

d = 110 km
train A = starts @ 7.00 with speed = 20 km
train B = starts @ 8.00 with speed = 25 km *(5kms difference A & B)

So, A+B=45 kms && d = 110
---> Time = d/s = 110/45 (after cancellation = 22/9)
---> Now add 5 (difference kms between 2 trains speed) to 22 = 27.
---> Now divide 27/9 = 3
---> Add 3 am to 7 am = 10 am.

**Here the difference in time is only 1 hr so added only 5 km's extra.

If the time difference was 2 hrs then we 10 and so on. If the answer you get doesn't match with the options then choose the closest options. The simple reason is time has 60 min where as when you are actually calculating it is of 100. Hope you'll are understanding.

HOPE THIS WORKS I WAS ACTUALLY TRYING TO MAKE SOME EASY SHIT SO THAT THIS TYPE OF SUMS BECOMES EASY FOR THE US :-)

Hi, @Chai.

I got 1:25 PM. Is this correct?

If the train was late by 3 hours and 12 minutes, then calculate the nearest hours.

@Yuvaraj, Thanks.

@ANISH MISHRA: Let the speed of the train P be xkm/hr and Q be ykm/hr.

After 6hrs, P would have travelled 6xkm (distance=speed*time) and similarly Q would have travelled 6ykm. Given, the distance between P and Q is 528, Hence,

6x + 6y = 528 -> (i).

Also, given that P having travelled 8km/hr more than Q. So,
x = y + 8 -> (ii).

Solving equation (i) & (ii),

x = 48km/hr (speed of train P).
y = 40km/hr (speed of train Q).

Here, the first train is started at 7:00 am at 20 km/h and the second train started at 8 am at the speed of 25 km/ h.

Train first started at 7 am @ 20 km/h.

7 am to 8 am covers =20 km
8 am to 9 am covers = 40 km
9 am to 10 am covers =60 km
10 am to 11am covers = 80km
11 am to 12 it covers 100 km


Train second started at 8am @ 25 km/h.

8 am to 9 am train covers = 25 km
9 am to 10 am it covers = 50 km
10 am to 11 am it covers = 75 km
11 am to 12 it covers = 100km

Now, both it covers 100 km at 12 o'clock. then how these 2 train meets each other at 10 am please help me, sir.

Thanks @Manish Dabhi.

Your explanation is very useful.

Simple formula to be remembered.

Total Time Taken = (d = s2 * t)/s1 + s2.

Where d = 110km, s2 = 25kmph, s1 = 20kmph, t = (8:00am - 7:00am) = 1hr.
From that we get 3hrs.

Therefore required Time is (7:00am + 3hrs) = 10:00Am.

Distance between two stations A and B is 100 km, two trains with speed 60 km/h and 40 km/h are running towards each other. What is the distance from station A where both trains will meet?

Can anyone find the answer?

60 km as relative speed of both the trains is 100 km/hr and
distance = 100km.

Then time taken to meet = distance/speed(relative).
T = 100/100 = 1 hr

So the trains will meet each other after 1 hour so,
Distance covered by first train in 1 hour = 60km/hr * 1hr = 60 km,
Distance covered by second train in 1 hour = 40km/hr * 1hr = 40 km,
Therefore, the distance from station A where both trains will meet = 60km.