Addition and Multiplication Rules of Probability with Venn and Tree Diagrams

MathematicsProbabilityAges 16–17

A Venn diagram with areas proportional to probability: drag event B closer to or farther from A to change P(AB), and instantly see P(A ∪ B) = P(A) + P(B) − P(AB), and when the two events are mutually exclusive or independent. A two-step tree diagram shows P(B|A), P(B|Ā), and the joint probabilities; a random-toss button compares experimental frequency with theoretical probability.