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:
45 km/hr
50 km/hr
54 km/hr
55 km/hr
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 34 of 48.

Prosenjit said:   8 years ago
Let the speed of the train x in one second.

So their combined speed=x-{5000/(60*60)}=x-1.39 in one second,
so, 125/x-1.39=10,
x=13.89 (in one second),
So 50000m=50 km in hour.

Imran said:   7 years ago
@Nivetha.

(x-5) is additional speed for overcrossing, the relative speed is 50-5=45. So here answer is 50 because (x-5) is crossing speed.

Bijayalaxmi priyadarsini said:   7 years ago
Hello please solve this question.

A 180meter long train crosses a man walking the same direction at a speed of 7. 2km per hour in 10 seconds what is the speed of train?

Ladura said:   7 years ago
What is the distance covered by the man in 10 seconds?

Dk singh said:   7 years ago
I think, 18/5 is seconds per meter not metres per second.

Kumud Singh said:   7 years ago
1 km = 1000 meters.
1 hr = 3600 seconds.

1 km/hr = 1000/3600 m/s.
= 10/36 m/s.
= 5/18 m/s.

@Gilbert & Dk Singh.
Therefore 1 km/hr = 5/18 m/sec.

Similarly, the reciprocal of m/sec is used to calculate km/hr.

Kumud Singh said:   7 years ago
@Ladura.

Distance covered by the man in 10 sec,
Speed = 5*5/18 = 25/18 m/sec,
Distance = 25/18*10 = 125/19 m.

Andrews Anbarasu said:   7 years ago
Your explanation is good @Ravi.

Thanks all.

Koser said:   7 years ago
Why is it divided by 125/10?

Shivam tomar said:   7 years ago
Speed of the train relative to man = 125/10 m/sec.

I am confused in this step, please clarify it.


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