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:
478 comments Page 48 of 48.
Rohan said:
5 years ago
No, it's wrong!
At last, speed came 45km. Now since it's in the same direction hence we will subtract, right.
So S=S (train (since its bigger value) - the speed given (5) ) ==>45-5 = 40.
Speed cannot be negative hence we always subtract smaller speed value FROM bigger speed value in the case for the same direction!
At last, speed came 45km. Now since it's in the same direction hence we will subtract, right.
So S=S (train (since its bigger value) - the speed given (5) ) ==>45-5 = 40.
Speed cannot be negative hence we always subtract smaller speed value FROM bigger speed value in the case for the same direction!
Qasim said:
4 years ago
The train and the man are moving in the same direction we have to use subtraction.
Here, we have to find the value of X. So for that, we have to keep X separate either left side or right.
Shift 45 to left and x to right. Because we are shifting, the sign will be change (positive to negative & negative to positive).
x-5 = 45
-5 - 45 = -x
-50 = -x ....(- - = + , so - - canceled)
x = 50.
Here, we have to find the value of X. So for that, we have to keep X separate either left side or right.
Shift 45 to left and x to right. Because we are shifting, the sign will be change (positive to negative & negative to positive).
x-5 = 45
-5 - 45 = -x
-50 = -x ....(- - = + , so - - canceled)
x = 50.
Namith said:
4 years ago
What is the difference between the relative speed of train and the speed of the train? Anyone, please explain.
Naveen said:
4 years ago
I can't understand this sum please anyone explain me briefly.
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.
Abinaya said:
4 years ago
Why we should reciprocal 5/18 to 18/5? Please explain.
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.
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