Axiomatic approach to probability
Probability theory · Mathematics
Study notes
Q: Using axioms, prove P(A') = 1 - P(A). A and A' are disjoint, and A union A' = S. By axiom 3: P(A union A') = P(A) + P(A'). By axiom 2: P(S) = 1. So 1 = P(A) + P(A'), giving P(A') = 1 - P(A).