# A train 125 m long passes a man, running at 5 km/hr in the same direction in............What is the speed of the train ?

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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.
What is the speed of the train ?

posted Dec 9, 2015

let speed of train be X m/s
so,
{(X-5)*9/3600}=125/1000
=>X-5 =1(25/9)*(18/5)
=>X-5 =50
=>X =55 km/hr

Speed of train=s1=x kmph
speedof man=s2=5kmph
Relative speed =s=(s1-s2)=(x-5)kmph
Time=10sec=10/3600hr
length of train=d=125m=125/1000km
d=t*s
125/1000=(10/3600)*(x-5)
x=50kmph
Ans:speed of the train is 50kmph

Speed of the train relative to man = 125/10 m/sec
=>25/2 m/sec
=>(25/2)*18/5
=> 45 km/hr.
Let the speed of the train be x km/hr. Then, relative speed = (x - 5) km/hr
so
x - 5 = 45
x = 50 km/hr
speed of train = 50 km/hr

I believe the correct answer is 50km/hr, though I found it in a much more circuitous way than the people below.

answer Jan 6, 2018 by anonymous

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