Probability Formulas
Probability formulas for permutations, combinations, Bayes theorem, binomial distribution, normal distribution, and expected value.
Expected Value
Reference for expected value E[X] = Σ x · P(x). The probability-weighted average of outcomes. Foundation of decision theory, gambling, and insurance.
Bayes' Theorem
Reference for Bayes' Theorem: P(A|B) = P(B|A) × P(A) / P(B). Update probabilities given new evidence. Foundation of Bayesian inference, machine learning, and medical testing.
Combinations and Permutations
Reference for permutations P(n,r) = n!/(n-r)! and combinations C(n,r) = n!/[r!(n-r)!]. Covers order vs no order with lottery and seating examples.