Problem 42 of 7
Find the missing event probability from addition-rule data P(A or B)=65%, P(B)=40%, P(A and B)=15%.
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solve for P(A) or P(B).
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Solve algebraically from P(A or B)=P(A)+P(B)-P(A and B).
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Solution
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1. Write the addition rule.
2. Substitute the known probabilities.
3. Isolate the missing marginal probability.
Use the worked steps, then substitute the final answer back into the original relationship to confirm it satisfies the prompt.
Treating P(A and B) as an amount to add twice.