Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 7)
7.
Two trains of equal length are running on parallel lines in the same direction at 46 km/hr and 36 km/hr. The faster train passes the slower train in 36 seconds. The length of each train is:
Answer: Option
Explanation:
Let the length of each train be x metres.
Then, distance covered = 2x metres.
Relative speed = (46 - 36) km/hr
| = |  |
10 x | 5 |  m/sec |
| 18 |
| = | |
25 | m/sec |
| 9 |
 |
2x | = | 25 |
| 36 | 9 |
2x = 100
x = 50.
Discussion:
232 comments Page 21 of 24.
Durgesh Kumar Gupta said:
7 years ago
Why not consider the length of the faster train? Please explain me.
Rgvkalp said:
7 years ago
We should consider also the length of the two trains as the faster train can overcome by its length and the slower train.
Therefore, the distance travelled by fa aster train is 2x.
Therefore, the distance travelled by fa aster train is 2x.
Ritika said:
7 years ago
Thanks, @Prati.
You explained it in the very simple way.
You explained it in the very simple way.
Kiran H said:
7 years ago
(Length of a train+Length of the train)/(time is taken by the train to cover the length) = Relative speed of two trains.
Let X be the length of the train.
(X+X)/36 = (46-36) {in km/hr convert it into m/s),
2X/36 = 10*(5/18),
X/18 = 50/18.
Therefore X= 50.
Let X be the length of the train.
(X+X)/36 = (46-36) {in km/hr convert it into m/s),
2X/36 = 10*(5/18),
X/18 = 50/18.
Therefore X= 50.
Swadhin said:
7 years ago
Thanks everyone.
UMAR farooq said:
7 years ago
First, it has to pass its complete length then it crosses the slowest train means;
First it takes 18 sec to travel its own length then it takes another 18 sec to cross the slowest train that's why 2x it is taken.
First it takes 18 sec to travel its own length then it takes another 18 sec to cross the slowest train that's why 2x it is taken.
Sunil said:
7 years ago
Since they are in same speed u,v.
We take u-v=46-36=10km/hr,
10*5/18=25/9,
So now we know the speed and time,
25/9 * 36 = 100.
As we calculated for the 2 trains we require only the length of one train so we take 100/2=50.
We take u-v=46-36=10km/hr,
10*5/18=25/9,
So now we know the speed and time,
25/9 * 36 = 100.
As we calculated for the 2 trains we require only the length of one train so we take 100/2=50.
Tejaswini said:
7 years ago
How did you take 2x?
Myuri said:
7 years ago
@Tejaswini.
Our question is to find the length of each train. So first we want to find both the length of the trains (2x), here x is a length of one train. So only take 2x.
Our question is to find the length of each train. So first we want to find both the length of the trains (2x), here x is a length of one train. So only take 2x.
Sumit Bhagat said:
7 years ago
If length of each train is supposed as x. Then how could distance cover is 2x?
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