Product rule

Theorem taught in Random experiments and probability, part of Probability

Product rule

Type Theorem
Taught in Random experiments and probability
Part Probability
Questions using it 1

If \mathbb{P}(A_1\cap\cdots\cap A_{n-1})>0, then

\mathbb{P}(A_1\cap\cdots\cap A_n) =\mathbb{P}(A_1)\,\mathbb{P}(A_2\mid A_1)\,\mathbb{P}(A_3\mid A_1\cap A_2)\cdots\mathbb{P}(A_n\mid A_1\cap\cdots\cap A_{n-1}).

Each factor is the definition of conditional probability, and the intermediate intersections cancel.

Used in

See also

Conditional probability · Law of total probability · Sample space · Event · Probability measure · Properties of a probability · Equally likely outcomes · Four ways of counting draws

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