# What will be the train’s average speed over the entire journey?

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A train covers its outward journey at 81 mph.
It returns, over exactly the same distance at 64.8 mph.

What will be the train’s average speed over the entire journey?

posted Sep 2, 2014

Its 72 MPH.

let train covers outword journey=81 miles
then total distance train covers=81+81=162 miles
total time=1+(81/64.8)
=2.25
average speed =total speed/total distance/total time
=162/2.25
=72mph

A train covers its outward journey at 81 mph.
And returns, over exactly the same distance at 64.8 mph
so average speed of train = (2*81*64.80)/81+64.8
=10497.6/145.8
=72 mph

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