The Math Forum

Ask Dr. Math - Questions and Answers from our Archives
Associated Topics || Dr. Math Home || Search Dr. Math

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!   
Associated Topics:
Middle School Word Problems

Search the Dr. Math Library:

Find items containing (put spaces between keywords):
Click only once for faster results:

[ Choose "whole words" when searching for a word like age.]

all keywords, in any order at least one, that exact phrase
parts of words whole words

Submit your own question to Dr. Math

[Privacy Policy] [Terms of Use]

Math Forum Home || Math Library || Quick Reference || Math Forum Search

Ask Dr. MathTM
© 1994- The Math Forum at NCTM. All rights reserved.