CS 2104 Problem Solving in Computer Science           Mini-writing Assignment 2
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This is a purely individual assignment.  Solve the given problem.  Write your 
solution and your explanation of how you solved the problem in this file
and turn it in by the specified due date.  Submit only plain text files for
this assignment!
	
Remember that the evaluation of your submission will depend primarily on the 
completeness and clarity of your explanation.
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The Problem:
	
A driver buys new tires for her car on January 1, including a new spare tire 
(the car uses a full-size spare tire).  When she finishes using the car on 
December 31, she has driven the car exactly 16,000 miles since she bought the
new tires.

During the year, she had her tires rotated periodically, so that each tire
has been in use for the same number of miles at the end of the year.  

Rotating the tires involves choosing one of the tires that is mounted on the 
car to be the spare tire, and mounting the spare tire and the other three 
tires on the car so those tires will be used for the next time period.

For how many total miles is each of the five tires in use?

Answer:
Each tire was in use for 12,800 miles.

Analysis:

If each tire was on the car (in use) for the same number of miles, then each
tire was also serving as the spare for the same number of miles.  Therefore,
each tire served as the spare for 1/5 of the total mileage, or 3200 miles.

Hence, each tire was in use for 16,000 - 3200 = 12,800 miles.