If I have 5 crayons (red, orange, yellow, green, blue) and I randomly choose 4, what are the chances that I do NOT choose green?

1 Answer
MathFact-orials.blogspot.com
Feb 1, 2017

1/5

Explanation:

We have five crayons, one of which is green. If I choose four crayons at random, what are the odds of not picking the green one?

First, let's find the number of ways I can choose four crayons from the five available. This is a combinations problem (the order we pick the crayons doesn't matter). The general formula for a combination is:

C_(n,k)=(n!)/((k)!(n-k)!) with n="population", k="picks"

C_(5,4)=(5!)/((4)!(5-4)!)=5

Of those 5, there's only 1 way to pick crayons that don't have green (red, orange, yellow, blue). So there's only a 1/5 probability of picking 4 crayons without getting a green.

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