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The Multiplication Rule
The multiplication rule states that the probability that
Learning Objective

Apply the multiplication rule to calculate the probability of both
$A$ and$B$ occurring
Key Points
 The multiplication rule is understood given that we know
$A$ has already occurred.  The multiplication rule can be written as:
$P(A \cap B) = P(B) \cdot P(AB)$ .  The events
$A$ and$B$ are defined on a sample space, which is the set of all possible outcomes of an experiment.  We obtain the general multiplication rule by multiplying both sides of the definition of conditional probability by the denominator.
Terms

multiplication rule
The probability that
$A$ and$B$ occur is equal to the probability that$A$ occurs times the probability that$B$ occurs, given that we know$A$ has already occurred. 
sample space
The set of all possible outcomes of a game, experiment or other situation.
Full Text
In probability theory, The Multiplication Rule states that the probability that
Or alternatively as:
The events A and B are defined on a sample space, which is the set of all possible outcomes of an experiment.
We obtain the general multiplication rule by multiplying both sides of the definition of conditional probability by the denominator. In general, the conditional probability can be defined as follows:
If
If
As an example, suppose that we draw two cards out of a deck of cards and let
and
The denominator in the latter equation is 51 since we know a card has been drawn already. Therefore, there are 51 left in total. We also know the first card was an ace, therefore:
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Key Term Reference
 conditional probability
 Appears in these related concepts: Conditional Probability, Basic Concepts, and Contingency Tables
 experiment
 Appears in these related concepts: Experimental Design, Primary Market Research, and Descriptive and Correlational Statistics
 independent
 Appears in these related concepts: Probability Histograms, The Rise of Independents, and Unions and Intersections
 independent event
 Appears in these related concepts: The Paradox of the Chevalier De Méré, Independence, and Review
 probability
 Appears in these related concepts: The Addition Rule, Theoretical Probability, and Rules of Probability for Mendelian Inheritance
 probability theory
 Appears in these related concepts: Applications of Statistics, Complementary Events, and Independence
 sample
 Appears in these related concepts: Defining the Sample and Collecting Data, Surveys, and Basic Inferential Statistics
Sources
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Cite This Source
Source: Boundless. “The Multiplication Rule.” Boundless Statistics. Boundless, 25 May. 2016. Retrieved 25 May. 2016 from https://www.boundless.com/statistics/textbooks/boundlessstatisticstextbook/probability8/probabilityrules34/themultiplicationrule1714445/