# What is the speed of the train?

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A train moves past a telegraph post and a bridge 264 m long in 8 seconds and 20 seconds respectively.
What is the speed of the train?

posted Jan 29, 2016

Let's length of the train =x meters
Speed of the train =y m/sec
Then x/y=8 => x=8y
Now, (x+264)=y
=> (8y+264)=20y
=> y=22
Therefore speed=22m/sec

let the length of the train be x metres and its speed by y m/sec.

Then, x/y = 8 => x = 8y

Now, x + 264 /20= y
=> 8y + 264 = 20y
=>12y=264
=>y=264/12
=> y = 22.

So Speed in m/sec= 22 m/sec
and Speed in km/hr=22x(18/5) =>79.2km/hr

let train speed= a m/s
and length of the train is x m
distance=speed*time
1.for telegraph
x=a*8
2.for bridge
x+264=a*20
put the value of x in second
a*8+264=a*20
by solving
a=22 m/s

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