Lecture 2 - Ch 4 - Basic Probability

We covered basic probability concepts.

The probability of some event, A, is:
P(A) = # of favorable outcomes / total possible outcomes

If we consider two events, A & B, they can be represented by a Venn diagram:
The entire yellow area, S, is the sample space.

P(A U B) = P(A) + P(B) - P(A /\ B)

We subtract P(A /\ B) because that overlap area (dark red in our Venn Diagram) is double counted if we just add P(A) and P(B).