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 2 of 48.
Moustafa Elhosiny said:
1 year ago
Sp of man = 5 * 5/18
= 25/18 m/sec.
Let Sp of train be x, then;
x - 25/18 = 125/10
So x = 125/10 + 25/18 = 125/9 m/sec.
So x = 125/9 * 18/5 =50 Km/h.
= 25/18 m/sec.
Let Sp of train be x, then;
x - 25/18 = 125/10
So x = 125/10 + 25/18 = 125/9 m/sec.
So x = 125/9 * 18/5 =50 Km/h.
(49)
Adesh Katiya said:
1 year ago
l = 125m,
u = 5km/hr,
v = ?
t = 10s.
u - v = 125/10 m/s,
u - v = 25/2 m/s,
u - v = 5*9 km/hr,
u - v = 45km/hr,
5km/hr - v = 45km/hr.
v = 50 km/hr.
Hence, option (B).
u = 5km/hr,
v = ?
t = 10s.
u - v = 125/10 m/s,
u - v = 25/2 m/s,
u - v = 5*9 km/hr,
u - v = 45km/hr,
5km/hr - v = 45km/hr.
v = 50 km/hr.
Hence, option (B).
(47)
Ashik Multani said:
2 years ago
Given
Length of train = 125m
Speed of man = 5km/hr = 5 * 5/18 = 25/18
Time = 10sec.
Speed = distance/time
Man running in the same direction so;
Let theh speed of the train is x.
speed = x - 25/18;
then by formula;
x - 25/18 = 125/10
x = 125/10 + 25 /18
x = 250/18 sec/m
Then;
convert into km/hr.
speed = 250/18 * 18/5.
speed = 50 => ans.
Length of train = 125m
Speed of man = 5km/hr = 5 * 5/18 = 25/18
Time = 10sec.
Speed = distance/time
Man running in the same direction so;
Let theh speed of the train is x.
speed = x - 25/18;
then by formula;
x - 25/18 = 125/10
x = 125/10 + 25 /18
x = 250/18 sec/m
Then;
convert into km/hr.
speed = 250/18 * 18/5.
speed = 50 => ans.
(45)
Ravina Sonawane said:
1 year ago
According to me, it should be 25/2 × 18/5 = 45.
(43)
Santhosh K said:
1 year ago
@All.
Why do we minus the speed of the man moving in the same direction? Please explain to me.
Why do we minus the speed of the man moving in the same direction? Please explain to me.
(39)
Mohammed Asif said:
3 years ago
The speed of train is 45 km per hour
And relative speed is 50 km per hour.
But in the question only speed of train is asked not the relative speed.
So, please either change the question and mention relative speed or change the answer to option A 45 km per hour which is the speed of train.
And relative speed is 50 km per hour.
But in the question only speed of train is asked not the relative speed.
So, please either change the question and mention relative speed or change the answer to option A 45 km per hour which is the speed of train.
(37)
Chinnupradhan said:
2 years ago
S = L/T.
S = 125/10
S = 25/2.
then,
M/sec to km/hr convert.
1km/hr = [1000m/3600sec] = 5/18m/sec,
m/sec = 18/5km/hr.
i.e
(25/2 * 18/5)km/hr,
45km/hr.
Therefore first train x-5 = 45.
X = 50 km/hr.
S = 125/10
S = 25/2.
then,
M/sec to km/hr convert.
1km/hr = [1000m/3600sec] = 5/18m/sec,
m/sec = 18/5km/hr.
i.e
(25/2 * 18/5)km/hr,
45km/hr.
Therefore first train x-5 = 45.
X = 50 km/hr.
(30)
Osaji Jeff said:
3 years ago
Why was the formula reversed from 5/18 to 18/5? Please explain me.
(29)
Phanikumar said:
5 months ago
How it comes 18/5? Anyone, explain to me.
(29)
Iliyas said:
3 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)
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