Compute compound event probabilities for a two-stage experiment using multiplication rule.
A probability tree represents sequential events as branches. Each path probability is the product of probabilities along its branches (multiplication rule). The total probability of any second-stage outcome is the sum across all paths reaching it (law of total probability).
Multiplication Rule
P(A and B) = P(A) × P(B|A)
Total Probability
P(B) = P(A)×P(B|A) + P(not A)×P(B|not A)
For sequential events, P(A and B) = P(A) × P(B|A). You multiply along the branches of the tree.
Sum the probabilities of all paths that end in that outcome. This is the law of total probability.