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?
[A].
9 a.m.
[B].
10 a.m.
[C].
10.30 a.m.
[D].
11 a.m.
Answer: Option B
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.
Amit Kr. Soni said:
(Sat, Aug 14, 2010 02:46:37 PM)
Hi Shri,
We can write here
(X-1) b'coz train 'B' starts travelling 1 hr later agains train 'A'.
So, At the end, train B will travel 1 hr short, out of full running time to meet each other. i.e 'X'
So, we can write total time for train 'B' = (X-1)
Thanks
Sathya said:
(Thu, Aug 26, 2010 02:35:53 AM)
Though the train B starts 1 hour late than train A, The speed of the train varies.
Easwar said:
(Sun, Nov 14, 2010 06:28:30 AM)
A train leaves a point A at 5 p.m. and reaches another point B a 11 p.m. Another train leaves point B at 7 p.m. and reaches point A at 10 p.m. At what time will the two trains meet?
8 : 15 p.m.
8 : 30 p.m.
8 : 20 p.m.
8 : 00 p.m.
can anyone solve this problem
Randhir said:
(Wed, Nov 17, 2010 09:18:07 PM)
hi Easwar,
The speed of one train is twice the other so let
speed of 1st train is Y.
speed of 2nd train is 2Y.
then distance between point A and B is 6Y.
Suppose they meet x hours after 5 a.m.
Distance covered by 1st train in X hours = YX km.
Distance covered by B in (X - 2) hours = 2Y(X - 2) km.
Therefore YX + 2Y(X - 2) = 6Y
=> YX + 2YX - 4Y = 6Y
=> 3YX = 10Y
=> X =10 / 3 (in hours)
=> X =10/3*60 (because converting into minutes)
=> X =200 minutes
200 minutes means 3 hour 20 minutes
So, they meet at 8 : 20 p.m.
Erererer said:
(Sat, Nov 27, 2010 05:30:28 PM)
X=3 how it convet to 10 am
Easwar said:
(Tue, Dec 7, 2010 02:09:11 PM)
Hi Erererer,
It was assumed that trains r meeting after x hours,
so 5 pm(starting time) + 3.20 = 8.20pm
Thanks Randhir.....
Faisal said:
(Mon, Jan 3, 2011 03:51:32 AM)
what if we say they meet after 8AM
Distance covered by B in x Hrs =25X
Distance covered by A in (x-1)Hrs = 20(x-1)
25x+20(x-1)=110
25x+20x-20=110
25x+20x=130
45x=130
x= 2.8 ( Which in incorrect how come )
Mahe said:
(Thu, Feb 3, 2011 05:17:39 AM)
@Faisel,
If they meet 8am then
Distance covered by b in xhrs is 25x
Distance covered by a in(X+1)HRS=20(X+1)
(x+1) coz v r considering 1 hr aft train A has started..
So,
25X+20(X+1)=110
45X=90
X=2
Hence 8am + 2 = 10am
Nayana said:
(Tue, May 17, 2011 10:29:00 PM)
@Randhir
In the problem what you have solved above,the distance between point A and B is 6Y. I am not getting how you got 6Y. Can you please explain me that?
Nithi said:
(Mon, May 23, 2011 12:55:15 PM)
@Randhir
I too not getting tht 6y concept..pls explain me...
Teena said:
(Mon, May 30, 2011 06:37:38 AM)
I dint get how x-1 term is used.
Gai3 said:
(Thu, Jun 23, 2011 06:39:50 AM)
According to this problem first we have to consider that both trains A & B are start at same time then only we can arrive the answer.
In question it is given that, A train starts at 7 a.m. and B train starts at 8 a.m.
Let starting time for A train = x
and starting time for B train = x-1 .
Sudha said:
(Thu, Jul 28, 2011 08:14:33 PM)
@Nayana,
We know that distance= speed*time
So, distance = y*6 = 6y
Calculate time between 5pm and 11pm, so totally 6 hours.
Thanks.
Gayatri said:
(Fri, Aug 26, 2011 07:26:24 PM)
@Easwar
The speed of one train is twice the other so let
speed of 1st train is Y.
speed of 2nd train is 2Y.
then distance between point A and B is 6Y.
Suppose they meet x hours after 5 a.m.
Distance covered by 1st train in X hours = YX km.
Distance covered by B in (X - 2) hours = 2Y(X - 2) km.
Therefore YX + 2Y(X - 2) = 6Y
=> YX + 2YX - 4Y = 6Y
=> 3YX = 10Y
=> X =10 / 3 (in hours)
=> X =10/3*60 (because converting into minutes)
=> X =200 minutes
200 minutes means 3 hour 20 minutes
So, they meet at 8 : 20 p.m.
Hii Randhir How come distance between point A and B is 6Y? Please explain.
Randhir said:
(Thu, Sep 22, 2011 09:31:19 AM)
@Gayatri, nithi, nayana
Speed=distance/time
1st train leaves a point A at 5 p.m. and reaches another point B a 11 p.m.that means time taken by train 6 hours.
Time = 6 hour
Speed of the 1st train is Y
Speed = Y km/h
Distance= speed*time (because speed=distance/time)
Distance= Y * 6 = 6Y
if you are still not getting my point then comes to train 2nd
2nd train leaves point B at 7 p.m. and reaches point A at 10 p.m. that means time taken by train 3 hours.
Time = 3 hour
How x=3 is converted into 10, please tell me any one.
Jammy said:
(Sat, Oct 22, 2011 08:54:46 PM)
3 = 3 hour.....therefore 7 a.m + 3 hour = 10 a.m
Yogi said:
(Tue, Nov 22, 2011 01:24:09 AM)
Actually I didn't understand this problem how do you get 10 AM as answer please would anyone get rid of these problem am not getting it.
Yuvaraj said:
(Thu, Dec 15, 2011 06:42:05 PM)
One more easy method to solve such problems.
Given that distance between two stations is 110km.
First trains speed is 20kmph and starts at 7 am
2nd trains speeed is 25kmph and starts at 8 am.
So at 8 am, the distance covered by first train is 20 kms.
Now remaining distance to cover is (110-20 = 90 km).
The relative speed of both the trains is 20+45 = 45 kms.
So it will take 2 hours to cover 90 km.
Hence the trains will meet after 2 hours from 8am i.e. at 10 am.
Knn said:
(Fri, Dec 30, 2011 05:36:54 AM)
Yuvraj. Cool answer!
Damodar Narayan said:
(Fri, Jan 27, 2012 06:32:26 PM)
A----------110---------B 7am
A---------90--------B 8am(Speed of the 1st train is 20 km/h)
20x + 25(x - 1) = 110
45x = 135