Question
P(A) = 1/13 P(B) = 1/4 P(A and B) = 1/52 P(A or B) = ?
Answer
$$ P(A \text{ or } B) = \dfrac{ 4 }{ 13 } $$
Explanation
To find $ P(A \text{ or } 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:
$$ \begin{aligned} P(A \text{ or } B) &= P(A) + P(B) - P(A \text{ and } B) \\ P(A \text{ or } B) &= \frac{ 1 }{ 13 } + \frac{ 1 }{ 4 } - \frac{ 1 }{ 52 } \\ P(A \text{ or } B) &= \frac{ 4 }{ 13 } \end{aligned}$$This page was created using
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