Probability

Counting Methods: r-List (with replacement), Permutations (nPr), Combinations (nCr) Random Experiment, Sample Space Ω & Events Union (A ∪ B), Intersection (A ∩ B), Complement (Ā) Incompatible (Mutually Exclusive) Events Venn Diagrams — visual explanations Probability Formula: P(A) = Card(A) / Card(Ω) Key Rules: Complement, Addition, De Morgan's Law Conditional Probability: P(B/A) = P(A ∩ B) / P(A) Independent vs Dependent Events Tree Diagrams — how to build and read them Total Probability Formula Bayes' Theorem (reverse tree direction) Worked Examples: balls in a bag, school surveys, factory defect problems