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14.5: Summary of Rules for Calculating Probabilities

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    95141

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    1. Events that are Certain to Occur: If A is certain to be true, Pr(A) = 1.
    2. Events that are Certain not to Occur: If A is certain to be false, Pr(A) = 0.
    3. Negations: Pr(~A) = 1 - Pr(A).
    4. Disjunctions with Incompatible Disjuncts: If A and B and incompatible, Pr(A or B) = Pr(A) + Pr(B).
    5. Conjunctions with Independent Conjuncts: If A and B are independent, Pr(A & B) = Pr(A) + Pr(B).
    6. Disjunctions: Pr(A or B) = Pr(A) + Pr(B) - Pr(A & B).
    7. Definition of Conditional Probability: Pr(A|B) = Pr(A & B)/Pr(B).
    8. Conjunctions: Pr(A & B) = Pr(A) x Pr(B|A).

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