# Bayes' theorem

play*noun*\ˈbāz-\

*or*

*less commonly*## Bayes theorem

*or less commonly*

## Bayes's theorem

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Definition of *Bayes' theorem*

: a theorem about conditional probabilities: the probability that an event A occurs given that another event B has already occurred is equal to the probability that the event B occurs given that A has already occurred multiplied by the probability of occurrence of event A and divided by the probability of occurrence of event B

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Origin and Etymology of *bayes' theorem*

Thomas *Bayes* †1761 English mathematician

First Known Use: 1830

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