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Desired outcome counting with letters

Counting ways to pick N vowels from M vowels in a set of tiles

This math skill teaches how to calculate the number of ways to choose a subset of vowels from a set of vowels, using combinations. It emphasizes understanding and applying the formula for combinations, represented as "n choose k", and calculating it using factorials.

Learn desired outcome counting with letters

Teaching Transcript

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How many different ways can we draw 2 vowels from this set of tiles?

The important thing to note is that only the vowels matter, we have 3 of them, and we are looking to pick 2 of the 3 in any order.

So that's 3 choose 2. We can write it in either notation, in the first, its the 3 first and the 2 second to mean 3 choose 2. In the bracketed, or binomial notation, it's the 3 on top.

The factorial equation for 3 choose 2 is 3 factorial, divided by, 2 factorial times 3 - 2 factorial.

If we calculate that out, that's 3 ways to pick 2 vowels.

Skill Practice

Counting ways to pick N vowels from M vowels in a set of tiles

Test your understanding of desired outcome counting with letters by practicing it! Work through the below exercises to use it in practice.