I’ve had some statistics courses but why would I ever remember something like that at a time when I actually needed it.

If you’re in the same boat, here’s some refreshers to help along the way.

There’s a Probability textbook over at Google books.

The Subtraction Rule of Probability

The Addition Rule of Probability

The Multiplication Rule of Probability

There’s combinatorics and the associated permutations.

Oh, and a little on factorials.