Aptitude - Problems on Trains - Discussion

Discussion Forum : Problems on Trains - General Questions (Q.No. 30)
30.
Two stations A and B are 110 km apart on a straight line. One train starts from A at 7 a.m. and travels towards B at 20 kmph. Another train starts from B at 8 a.m. and travels towards A at a speed of 25 kmph. At what time will they meet?
9 a.m.
10 a.m.
10.30 a.m.
11 a.m.
Answer: Option
Explanation:

Suppose they meet x hours after 7 a.m.

Distance covered by A in x hours = 20x km.

Distance covered by B in (x - 1) hours = 25(x - 1) km.

Therefore 20x + 25(x - 1) = 110

=> 45x = 135

=> x = 3.

So, they meet at 10 a.m.

Discussion:
92 comments Page 2 of 10.

Manisha said:   7 years ago
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.
(1)

Mano said:   6 years ago
How we are obtained the 10 ?

Please explain it.
(1)

Syed Abdul Raqeeb said:   5 years ago
Why x-1 is used in this sum, and how x=3 and how the answer is 10? Please explain.
(1)

Gokul Ramakrishnan said:   4 years ago
@Chai.

I got 2.25 is it correct or not?
(1)

Sonic said:   9 years ago
Why it's taken x-1 but not x+1 because train 2 starts 1 hr later?

Anna said:   7 years ago
Thank you very much @Yuvaraj.

Ayush said:   9 years ago
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.

Ankita said:   9 years ago
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?

Sourav Pal said:   9 years ago
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.

Rabiul said:   9 years ago
Thanks @Manish Dabhi.

Your explanation is very useful.


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