| A | B |
|---|
| Sample space | collection of all possible outcome values - P(S) = 1 |
| Disjoint events | Two events are disjoint if they have no outcomes in common. |
| Addition Rule | If A and B are dsjoint events, then the P(A or B) = P(A) + P(B) |
| General Addition Rule | For ANY two events A and B, the probability of A or B is P(A or B) = P(A) + P(B) - P(A and B) |
| Conditional Probability | P(B/A) = P(A and B)/P(A) |
| Independence | Two events are this if knowing whether one event occurs does not alter the prob. that the other event occurs. |
| Multiplication Rule | If A and B are idependent events, then P(A and B) = P(A) x P(B) |
| General Multiplication Rule | For any two events A and B P(A and B) = P(A) x P(B/A) |
| Tree Diagram | A display of conditional events or probabilities that is helpful in thinking through conditioning. |
