- Probability = Number of successes / Total number of possibilities

- Independent probabilities can be multiplied.

1) How many days in a week, and how many of those are Saturday?

2) How many days in a week, and how many of those are not Saturday?

3) Take the answer for two, and now you have two independent probabilities.

4) Same as 3) except you have 3.

5) Same as 4) except you have 20.