The rule is a rule from the probability account to calculate the probability of the association of two events G1 and G2, that is, the probability of G1 or G2 occurring. Disjunct Events: Special Rule
For disjuncte, ie, exclusively, events, it is simple that the probability of the association is the sum of the individual chances: P ( G 1 & # x222A; G 2 ) = P ( G 1 ) + P ( G 2 ) {\displaystyle P(G_{1}\cup G_{2})=P(G_{1})+P(G_{2})} . Random Events: General Rule
For random events: P ( G 1 & # x222A; G 2 ) = P ( G 1 ) + P ( G 2 ) & # x2212; P ( G 1 & # x2229; G 2 ) . {\displaystyle P(G_{1}\cup G_{2})=P(G_{1})+P(G_{2})-P(G_{1}\cap G_{2}).}
This rule can be understood by double counting on the individual odds when adding the individual odds. Also see
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