Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 13)
13.
Two trains, each 100 m long, moving in opposite directions, cross each other in 8 seconds. If one is moving twice as fast the other, then the speed of the faster train is:
Answer: Option
Explanation:
Let the speed of the slower train be x m/sec.
Then, speed of the faster train = 2x m/sec.
Relative speed = (x + 2x) m/sec = 3x m/sec.
 |
(100 + 100) | = 3x |
| 8 |
24x = 200
| x = |
25 | . |
| 3 |
| So, speed of the faster train = | 50 | m/sec |
| 3 |
| = |  |
50 | x | 18 |  km/hr |
| 3 | 5 |
= 60 km/hr.
Discussion:
74 comments Page 3 of 8.
Swetha said:
1 decade ago
Hi @Raja,
5/18 is to convert KM to Meters.
18/5 is to convert Meters to KM.
As, in question it is given in Meters but answer is in meters so have to convert Meters to KM. So we are using.
5/18 is to convert KM to Meters.
18/5 is to convert Meters to KM.
As, in question it is given in Meters but answer is in meters so have to convert Meters to KM. So we are using.
Roshan Kumar said:
4 years ago
Answer will be 30km/hr.
Because the simplification of 200/24 = 25/6.
But in the answer it's given as 25/3 that's why the answer is changed to 60 km/hr.
Because the simplification of 200/24 = 25/6.
But in the answer it's given as 25/3 that's why the answer is changed to 60 km/hr.
(1)
Kumaran6248 said:
1 decade ago
Here I wanna know! how we suppose to have 2x as fast train. Can any one suggest me"""If one is moving twice as fast the other""". And what about this?
Shiva said:
1 decade ago
Why you are all talking always 5/18 to convert kmph into m/sec, I can't understand that logic, please explain reason behind that. Thanks in advance.
Nagashree said:
1 decade ago
In the question they have mentioned that we have to find the train which is twice as fast the other hence we have to multipy (25 x 2)/3 = 50/3.
Fabarah Israr said:
4 years ago
Can someone please tell me, we are already multiplying 2 with x then why we are again multiplying with 2 with 25/6? Please explain me.
(1)
Akber said:
1 decade ago
Assume one train is moving with X speed than other is twice faster it means 2x
look normal speed =x
twice the above speed=2*x=2x
look normal speed =x
twice the above speed=2*x=2x
Anshul Saraf said:
1 decade ago
Here both trains will not travel the same distance of 100 m. However the sum of distance travelled by both trains will be 200.
Vel said:
1 decade ago
Hi seema rules wise we have to add the distance, relative speed based on the direction of both trains (same:-, opposite:+).
Nayana said:
1 decade ago
Hi Arun,
Here we are converting km/h to m/s
so 1km=1000 meters
1hr=3600 sec
1km/h=1000/3600 m/s
1000/3600=5/18 m/s
Here we are converting km/h to m/s
so 1km=1000 meters
1hr=3600 sec
1km/h=1000/3600 m/s
1000/3600=5/18 m/s
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