Probability Fundamentals

$P(A') = 1 - P(A)$

$P(A \cup B) = P(A) + P(B) - P(A \cap B)$

$P(A \cap B) = P(A) \times P(B|A)$

Independent: $P(A \cap B) = P(A) \times P(B)$.

Mutually exclusive: $P(A \cap B) = 0$.

$P(A|B) = \frac{P(A \cap B)}{P(B)}$

• Tree diagrams: multiply along, add between paths.
• Venn diagrams: organise overlapping events.
• Tables: two-way tables for conditional probability.