11-1 Permutations and Combinations

Objectives To count permutations

To count combinations

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It is fairly easy to count the ways you can pick items from a short list. But, sometimes you have so many choices that counting the possibilities is impractical.

Essential Understanding You can use multiplication to quickly count the number of ways certain things can happen.

The Fundamental Counting Principle describes the method of using multiplication to count.

Here's Why It Works Making a tree diagram, you can see that there are 3 groups of 2 outfits, or 3 · 2 = 6 3 middle dot 2 equals 6  outfits, starting with the pants.

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You can extend the Fundamental Counting Principle to three or more events.

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