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### Average Speed

```
Date: 08/26/97 at 20:50:32
From: Patapol Pawananon
Subject: Algebra

A person travels up a hill at 10 mph. and back down at 20 mph. What is
the average speed for the entire trip?
```

```
Date: 08/27/97 at 08:02:34
From: Doctor Anthony
Subject: Re: Algebra

The answer is NOT 15 mph because he spends longer at the slower speed.

Let x = distance up the hill

Time up the hill =  x/10

Time down the hill =  x/20

Total time =  x/10 + x/20  = 3x/20
Total distance = 2x

Average speed =  2x/(3x/20)  = 40/3  =  13.333 mph

-Doctor Anthony,  The Math Forum
Check out our web site!  http://mathforum.org/dr.math/
```
Associated Topics:
Middle School Word Problems

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