Conditional Probability (VCE SSCE Mathematical Methods): Flashcards

Probability of event A given event B has occurred

$\text{Pr}(A \mid B)$

Given or knowing that

$\frac{\text{Pr}(A \cap B)}{\text{Pr}(B)}$ if $\text{Pr}(B) \neq 0$

No, order matters in conditional probability

$\text{Pr}(A \mid B) \times \text{Pr}(B)$

Multiply along branches, add across branches

$\text{Pr}(A \mid B)\text{Pr}(B) + \text{Pr}(A \mid B')\text{Pr}(B')$

Restricted to only outcomes where B happens

Multiply probabilities along that branch