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:
476 comments Page 43 of 48.
Nilesh838 said:
4 years ago
Good explanation, thanks.
Suraj kale said:
4 years ago
The object Man is also moving in the same direction as that of the train so the total distance covered should not be 125 meters.
It should be the (125+X).
Where X is the distance covered by man in 10 seconds.
It should be the (125+X).
Where X is the distance covered by man in 10 seconds.
Seshu said:
4 years ago
length = speed * time = 5 * 10 = 50.
(3)
Abinaya said:
4 years ago
Why we should reciprocal 5/18 to 18/5? Please explain.
Bithal Jena said:
4 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)
Kushal M V said:
4 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:
4 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.
Raghu k said:
4 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)
Moses Obia said:
4 years ago
Where was 18 got from? Please explain.
(6)
Bunny said:
4 years ago
Why the speed of the train is calculated by 125 meters by 10sec?
(6)
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