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+# Bayes’ Theorem
+
+## Formula
+P(A | B) = [P(B | A) × P(A)] / P(B)
+
+## Total Probability
+If A₁, A₂, …, Aₙ are exhaustive events:
+P(B) = Σ P(B | Aᵢ)P(Aᵢ)
+
+## When to Use
+- Conditional probability
+- Inverse probability problems
+
+## Common Mistakes
+- Forgetting total probability
+- Confusing P(A|B) with P(B|A)