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:
475 comments Page 18 of 48.
Akshay said:
1 decade ago
Why should multiply 18/5?
Deepak meena said:
1 decade ago
It's simple way.
We know that the speed of train is 125m/10s.
Then 125/10 = 25/2.
This is the speed of train in 1 second.
Now speed in 1 hr = 25/2*3600 = 45.
And men is going in 5km/1hr so speed of train is 50km/hr.
We know that the speed of train is 125m/10s.
Then 125/10 = 25/2.
This is the speed of train in 1 second.
Now speed in 1 hr = 25/2*3600 = 45.
And men is going in 5km/1hr so speed of train is 50km/hr.
Krish said:
1 decade ago
How to be solve this 25/2*18/5 = 45?
AAKASH said:
1 decade ago
125m/10s*18/5=45.
The man running in opposite direction at a speed of 5 km so 45+5=50.
The man running in opposite direction at a speed of 5 km so 45+5=50.
Ramkumar said:
1 decade ago
Why use 60*60/1000(18/5) I do not understand that?
Please explain.
Please explain.
Givid said:
1 decade ago
I have a doubt on question. Whose speed is 5km/hr? either the man's or train's? please explain.
Muhammed areeb said:
1 decade ago
Why use 60*60/1000(18/5) I do not understand that?
GwenBiz said:
1 decade ago
@Jothi,
x-5 = 45.
We add 5 to both sides so that we stay with x.
x-5+5 = 45+5.
Therefore,
So x = 50.
x-5 = 45.
We add 5 to both sides so that we stay with x.
x-5+5 = 45+5.
Therefore,
So x = 50.
Navi said:
1 decade ago
Hi @Swati look here let me explain:
L = Speed*time.
And,
Speed = length/time.
Length = 25/2.
Time = 5/18.
And,
25/2/5/18 = 25/2*18/5.
9*5 = 45km/hr.
x-5 = 45.
45+5 = x.
x = 50km/hr.
L = Speed*time.
And,
Speed = length/time.
Length = 25/2.
Time = 5/18.
And,
25/2/5/18 = 25/2*18/5.
9*5 = 45km/hr.
x-5 = 45.
45+5 = x.
x = 50km/hr.
Shibin said:
1 decade ago
Relative speed = x-5 (x is the speed of train).
(x-5)*5/18 = 125/10.
x-5 = 125*18/10*5.
x-5 = 125*9/25.
x-5 = 5*9.
x-5 = 45.
x = 50.
(x-5)*5/18 = 125/10.
x-5 = 125*18/10*5.
x-5 = 125*9/25.
x-5 = 5*9.
x-5 = 45.
x = 50.
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