multiplication law for probabilities

Show Summary Details

Quick Reference

Law for probabilities stating that if A and B are independent events then


and, in the case of n independent events, A1, A2,…, An,

P(A1A2 ∩…∩ An)=P(A1)×P(A2)×…×P(An).

This is a special case of the more general law of compound probability, which holds for events that may not be independent. In the case of two events, A and B, this law states that


For three events, A, B, and C, this becomes


There are six (=3!) alternative right-hand sides, for example P(C)×P(A|C)×P(B|CA). The generalization to more than three events can be inferred. For definitions of symbols, see conditional probability; intersection.

Subjects: Probability and Statistics.

Reference entries

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.