what is the basic rules of probability theory
We need a rule to guide us. Addition Rule 1: When two events, A and B, are mutually exclusive, the probability that A or B will occur is the sum of the probability of each event. P(A or B) = P(A) + P(B) Let's use this addition rule to find the probability for Experiment 1.
P(A or B) = P(A) + P(B) Addition Rule 2:: When two events, A and B, are non-mutually exclusive, there is some overlap between these events. The probability that A or B will occur is the sum of the probability of each event, minus the probability of the overlap.