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 35 of 48.
JEEVAN said:
9 years ago
Shortcut
125/10 = trains speed -mans speed.
Lowest form = trains speed - 5.
25/2 into km/h = 25/2 * 18/5.
= 5/1 * 9/1.
= 45km/h.
45km/h = trains speed - mans speed.
45km/h = trains speed - 5.
THEREFORE 5 + 45 = TRAINS SPEED (transposing method).
= 50km/h.
125/10 = trains speed -mans speed.
Lowest form = trains speed - 5.
25/2 into km/h = 25/2 * 18/5.
= 5/1 * 9/1.
= 45km/h.
45km/h = trains speed - mans speed.
45km/h = trains speed - 5.
THEREFORE 5 + 45 = TRAINS SPEED (transposing method).
= 50km/h.
Vinutha said:
9 years ago
Can anyone explain, how we will get to know that, the given length and time is for relative speed, and why can't it be related to speed of train?
Sushanth ratan said:
9 years ago
@Jothi.
-5 if it goes on the other side it becomes plus (+).
-5 if it goes on the other side it becomes plus (+).
Ajay said:
8 years ago
As per my calculation, 50 km/hr is the right answer.
Nishant said:
8 years ago
But it should have been given that we have to find the relative velocity of the man. So, 45km/hr should be the right answer.
Priyanka said:
8 years ago
Why we consider v=5 to subtract u - v?
Venkatesh said:
8 years ago
Thank you @Nagapriya.
Ganga said:
8 years ago
Why we subtract (x-5)?
Shailesh Hiremath said:
8 years ago
So, kilometre & minutes will be calculated as 1 km=1000 mtrs and 60 minutes =3600 seconds.
If you divide 3600/1000 = 5/18.
If you divide 3600/1000 = 5/18.
Sunil said:
8 years ago
Thank you all for the given explanations.
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