Probability.

11 lessons93 min2 simulations

Probability turns 'how likely' into a number. The chapter treats every event as a subset of a sample space, names the impossible, sure, simple and compound events, and combines events with complement, union, intersection and difference. It then sets out the three axioms any assignment of probabilities must satisfy, finds P(A) by adding outcome probabilities, specialises to equally likely outcomes where P(E) = n(E)/n(S), and proves the addition rule, which removes the overlap A ∩ B counted twice, and the complement rule P(not A) = 1 − P(A), using counting for larger sample spaces.

Also called: probability · Bayes' theorem · conditional probability