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 43 of 48.
Robi said:
7 years ago
@Omkar Tanpure.
What is the relative speed? And why 45 is called relative speed? Please explain me.
What is the relative speed? And why 45 is called relative speed? Please explain me.
Ramya said:
7 years ago
Can anyone Explain this problem to me? I didn't understand this.
Chandan Azad said:
7 years ago
T(time required) = Lt(length of train) + Lo(length of object)/ Ut(speed of Train)+,-Uo(speed of object) .
("-" when train and object goes in same direction.
"+" when train and object goes in opposite direction.)
10=(125+0)/(Ut-5*5/18).
Ut=125/9.
Ut=(125/9)*(18/5).
Ut=50km/hr.
("-" when train and object goes in same direction.
"+" when train and object goes in opposite direction.)
10=(125+0)/(Ut-5*5/18).
Ut=125/9.
Ut=(125/9)*(18/5).
Ut=50km/hr.
Hari kumar said:
7 years ago
50 is the right answer.
Lavanya said:
7 years ago
Why do we to subtract 45-5? please clarify that.
Narendra said:
7 years ago
In same direction, T. S-M. S = 125/10 * 18/5 = 45.
M.S = 5KMph.
T.S - 5 = 45.
T.S = 50sec.
M.S = 5KMph.
T.S - 5 = 45.
T.S = 50sec.
Abuthahir said:
7 years ago
X-5 = 45.
Here x = 45+5,
Then x = 50.
Here x = 45+5,
Then x = 50.
Anjali said:
7 years ago
Thanks all for explaining the answer.
Vinod said:
7 years ago
Thanks all for explaining the answer.
Muhammad Zulafqar said:
7 years ago
The simplest answer is;
10sec/1000Meter =0.01.
Then multiply with 5KM i.e 0.01 * 5000meter = 50KM.
10sec/1000Meter =0.01.
Then multiply with 5KM i.e 0.01 * 5000meter = 50KM.
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