In Figure 1, only two colors are needed in order to distinguish the center region from the region around it. |
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How many colors are needed to distinguish the regions in figure 2? _____ (we want the least number of colors needed) |
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How many colors are needed to distinguish the regions in figure 3? _____ |
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Figure 4 needs 4 colors for telling the regions apart. |
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The object is to use the least number of colors so that adjacent regions (those sharing some common boundary line) are colored differently. Good Luck!


