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?
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.
20x + 25(x - 1) = 110
45x = 135
x = 3.
So, they meet at 10 a.m.
Discussion:
92 comments Page 4 of 10.
Bhat ashraf said:
8 years ago
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.
Please answer it.
Swasti said:
8 years ago
How this 3 hr comes?
Mary said:
8 years ago
How to solve if they move in the same direction?
Basharat said:
8 years ago
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.
If they are in opposite directions just add their speeds if they are in same directions subtract their speeds.
Sachin said:
8 years ago
Here
V1 =20 km/hr.
V2 = 25km/hr.
Time of meet they
= 110-20/20 + 25.
= 2hr.
Then 8+2 = 10am.
V1 =20 km/hr.
V2 = 25km/hr.
Time of meet they
= 110-20/20 + 25.
= 2hr.
Then 8+2 = 10am.
Chittaranjan said:
8 years ago
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.
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.
Nikhil_vats said:
8 years ago
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.
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.
Hardik khatri said:
10 years ago
@Chai.
Why do we have to take the distance 390 when we add this covered by A after x hours and this covered by B after x-1 hours then why we equal it to 390 km?
Why do we have to take the distance 390 when we add this covered by A after x hours and this covered by B after x-1 hours then why we equal it to 390 km?
Praveen_Nayak said:
7 years ago
Thank you @Manish Dabhi.
Viswa said:
7 years ago
For equal starting time of two trains (ie 8am, 8am).
Train A cover a distance in one hour = 20km.
So total distance covered by two trains =110-20.
= 90km.
The relative speed of trains =20+25.
= 45kmph.
Two trains are meeting at a time of X hr.
The formula is;
90/X = 45,
X=2,
8am+2 = 10am.
Train A cover a distance in one hour = 20km.
So total distance covered by two trains =110-20.
= 90km.
The relative speed of trains =20+25.
= 45kmph.
Two trains are meeting at a time of X hr.
The formula is;
90/X = 45,
X=2,
8am+2 = 10am.
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