Thinking Mathematically (6th Edition)

Published by Pearson
ISBN 10: 0321867327
ISBN 13: 978-0-32186-732-2

Chapter 1 - Problem Solving and Critical Thinking - 1.3 Problem Solving - Exercise Set 1.3 - Page 40: 46


The minimum number of colors is 4.

Work Step by Step

For convenience, instead of coloring, the countries in the provided picture are filled with numbers, instead of colors, each number representing a different color. From the picture, we can see that it's possible to paint them so that no country has the same color as any of it's bordering countries with 4 colors. It's impossible to paint them all with 3 or less colors without 2 neighboring countries having the same color.
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