# Geo.8 Conditional Probability

In this unit, students extend what they learned about probability in grade 7 by considering events that are combined in various ways including both occurring, at least one occurring, and one event happening under the condition that the other happens as well. This unit introduces the relationship between probabilities of some combinations of events using the Addition Rule, $$P(\text{A or B}) = P(\text{A}) + P(\text{B}) - P(\text{A and B})$$. Conditional probability is discussed. In particular, the Multiplication Rule $$P(\text{A and B}) = P(\text{A | B}) \boldcdot P(\text{B})$$ is used to determine conditional probabilities as well as independence of events A and B. Independence is further explored using everyday language as well as through the equation $$P(\text{A | B}) = P(\text{A})$$ when events A and B are independent.