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 1 of 10.
Kaushal Parmar said:
2 months ago
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.
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.
Mohammed Nadhil said:
6 months ago
My logic answer:
At 7, distance covered, A =0 km, B = 0 km.
At 8, distance covered A = 20 km, B =0 km.
At 9, distance covered A = 40 km, B = 25 km.
At 10, distance covered, A = 60 km, B = 50 km.
At 11, distance covered, A = 80 km, B = 75 Km.
At 12, distance covered, A =100 Km, B = 100 k.
Correct me, if my logic is wrong.
At 7, distance covered, A =0 km, B = 0 km.
At 8, distance covered A = 20 km, B =0 km.
At 9, distance covered A = 40 km, B = 25 km.
At 10, distance covered, A = 60 km, B = 50 km.
At 11, distance covered, A = 80 km, B = 75 Km.
At 12, distance covered, A =100 Km, B = 100 k.
Correct me, if my logic is wrong.
(9)
Shiv said:
10 months ago
As A train starts at 7 am at 20kmph and B starts at 8 am at 25kmph.
The distance between them is 110 km.
As A starts an hour early at 8 am, A has travelled 20 km.
Now at 8 am, the distance between them is 110–20 km.
As of now, we have a distance as 90 km.
The relative speed is 45kmph.
Time = Distance/Speed.
Time = 90/45 = 2 hrs.
i.e after 2 hours, so 8 a.m + 2 hours = 10 a.m.
The distance between them is 110 km.
As A starts an hour early at 8 am, A has travelled 20 km.
Now at 8 am, the distance between them is 110–20 km.
As of now, we have a distance as 90 km.
The relative speed is 45kmph.
Time = Distance/Speed.
Time = 90/45 = 2 hrs.
i.e after 2 hours, so 8 a.m + 2 hours = 10 a.m.
(35)
Shalini said:
12 months ago
It's very interesting and useful to learn. Thanks.
(3)
Sumanth kumar said:
2 years ago
The correct option is B: 10 A.M.
We know, Time = Distance/speed.
Here, we have to consider the relative speed of two trains.
=> 20 km/hr + 25 km/hr = 45 km/hr (since they are moving in opposite directions)
Here, the distance between them cannot be taken as 110 km as train B didn't start at 7 A.M.
The distance train A would have covered from 7 A.M to 8 A.M will be =
20km/hr* 1hr= 20 km.
So, the distance between these two trains will become 110 km - 20 km = 90 km at 8 A.M.
So now, the time is taken for them to meet = 90 km/ 45 km/hr= 2 hrs.
They meet 2 hrs after 8 A.M i.e 10 A.M.
We know, Time = Distance/speed.
Here, we have to consider the relative speed of two trains.
=> 20 km/hr + 25 km/hr = 45 km/hr (since they are moving in opposite directions)
Here, the distance between them cannot be taken as 110 km as train B didn't start at 7 A.M.
The distance train A would have covered from 7 A.M to 8 A.M will be =
20km/hr* 1hr= 20 km.
So, the distance between these two trains will become 110 km - 20 km = 90 km at 8 A.M.
So now, the time is taken for them to meet = 90 km/ 45 km/hr= 2 hrs.
They meet 2 hrs after 8 A.M i.e 10 A.M.
(89)
Prasoon Kumar said:
3 years ago
I didn't get anything. Please help me to get this.
(3)
Raj said:
3 years ago
As A train starts at 7 am at 20kmph and B starts at 8 am at 25kmph.
The distance between them is 110km.
As A starts an hour early at 8 am A has travelled 20 km.
Now at 8 am distance between them is (110-20)km.
As of now we have a distance as 90km.
The relative speed is 45kmph.
Time = Distance/Speed.
Time = 90/45 =2 hrs.
The distance between them is 110km.
As A starts an hour early at 8 am A has travelled 20 km.
Now at 8 am distance between them is (110-20)km.
As of now we have a distance as 90km.
The relative speed is 45kmph.
Time = Distance/Speed.
Time = 90/45 =2 hrs.
(33)
Akshay k said:
4 years ago
Tell me that these two trains meet at what distance. Please anyone explain to me.
(3)
Gokul Ramakrishnan said:
4 years ago
@Chai.
I got 2.25 is it correct or not?
I got 2.25 is it correct or not?
(1)
Asmi said:
4 years ago
Here, how will get 110? Please explain.
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