I have 28 movies, 12 action and 16 dramas, what is the probability of randomly choosing 3 action movies?

The total ways of choosing any 3 movies from the 56 total is C(56,3) = 27720

And the total ways of choosing 3 of the 12 action movies is C(12,3) = 220

So

220 / 27720 = 1/126 = about .0079 = about .79%