Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 2)
2.
A train 125 m long passes a man, running at 5 km/hr in the same direction in which the train is going, in 10 seconds. The speed of the train is:
Answer: Option
Explanation:
| Speed of the train relative to man = |  |
125 |  m/sec |
| 10 |
| = | |
25 | m/sec. |
| 2 |
| = | |
25 | x | 18 | km/hr |
| 2 | 5 |
= 45 km/hr.
Let the speed of the train be x km/hr. Then, relative speed = (x - 5) km/hr.
x - 5 = 45 
x = 50 km/hr.
Discussion:
493 comments Page 7 of 50.
Osaji Jeff said:
4 years ago
Why was the formula reversed from 5/18 to 18/5? Please explain me.
(29)
Iliyas said:
4 years ago
m/sec = [1/1000 km] / [1/3600 sec]
= [1/1000] *[3600/1],
= [3600/1000].
= [18/5]km/hr.
= [1/1000] *[3600/1],
= [3600/1000].
= [18/5]km/hr.
(28)
Priyanka devi said:
5 years ago
@Rahul.
Great work, Thanks for explaining.
Great work, Thanks for explaining.
(7)
Bunny said:
5 years ago
Why the speed of the train is calculated by 125 meters by 10sec?
(6)
Moses Obia said:
5 years ago
Where was 18 got from? Please explain.
(6)
Raghu k said:
5 years ago
It is simple guys.
If we observe hint, her there should be the relative speed because the train and are travelling in the same direction so we (train) -v (man) T =Distance.
(120/10) (18/5) =v (t) -5.
45+5=v (t).
50=v (t).
If we observe hint, her there should be the relative speed because the train and are travelling in the same direction so we (train) -v (man) T =Distance.
(120/10) (18/5) =v (t) -5.
45+5=v (t).
50=v (t).
(8)
Kushal M V said:
5 years ago
They took 18/5 because the length of train is in meter and time given which passes the man is given in seconds. To convert m/s to km/ hr they multiplied with 18/5. And the answers also in km/hr.
(2)
Kushal M V said:
5 years ago
They took 18/5 because the length of train is in meter and time given which passes the man is given in seconds. To convert m/s to km/ hr they multiplied with 18/5. And the answers also in km/hr.
Bithal Jena said:
5 years ago
Solution:
Time = Distance/Speed.
Length of train=125m.
Speed of the person in the same direction is 5KM/hr i.e 25/18m/sec
the train takes 10 sec to cross i.e our time.
Let take x as the speed of the train.
So according to the above formula.
10 = 125/x-(25/18),
10 = 125 * 18/18x-25.
x = 13 * 18/5 m/sec.
To make it KM/hr we have to multiply it by the help of 18/5.
13*18/5 * 18/5 = 46km/hr.
So ans should be 46.
Time = Distance/Speed.
Length of train=125m.
Speed of the person in the same direction is 5KM/hr i.e 25/18m/sec
the train takes 10 sec to cross i.e our time.
Let take x as the speed of the train.
So according to the above formula.
10 = 125/x-(25/18),
10 = 125 * 18/18x-25.
x = 13 * 18/5 m/sec.
To make it KM/hr we have to multiply it by the help of 18/5.
13*18/5 * 18/5 = 46km/hr.
So ans should be 46.
(3)
Abinaya said:
5 years ago
Why we should reciprocal 5/18 to 18/5? Please explain.
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