Question
P(A) = 0.4 P(A and B) = 0.01 P(A or B) = 0.89 P(B) = ?
Answer
$$ P(B) = 0.5 $$
Explanation
To find $ P(B) $ we use an addition rule:
$$ \color{blue}{P(A \text{ or } B) = P(A) + P(B) - P(A \text{ and } B)}$$In this example we have:
$$ \begin{aligned} P(A \text{ or } B) &= P(A) + P(B) - P(A \text{ and } B) \\ 0.89 &= 0.4 + P(B) - 0.01 \\ P(B) &= 0.89 - 0.39 \\ P(B) &= 0.5 \end{aligned}$$This page was created using
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