A box contains 5 green hats and 4 blue hats and 3 hats are randomly selected from the box. Find the probability that at least one hat is blue.

Question

These problems are usually easy, but I am totally blanking on this. I've tried a handful of ways and got it wrong.

Answer 1

Hint:  The only way to not get any blue hats is if all 3 hats that are selected are green.  

 

So try finding P(GGG) [this is the probability that all 3 selected hats are green] and subtracting it from 1.  

 

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