Combined Events (Leaving Cert Mathematics): Quizzes

$P(A) + P(B) - P(A \text{ and } B)$

Either event $A$ or event $B$ (or both)

To avoid counting the overlap twice

$\frac{1}{4}$

$\frac{1}{13}$

$\frac{1}{52}$

$\frac{4}{13}$

$P(A) \times P(B \mid A)$

Both event $A$ and event $B$ occur

Events become dependent

$\frac{1}{17}$

$\frac{1}{221}$