Conditional probability

Definition

The probability that an event occurs given that another event has occurred. For example, $P(B\mid A)$ means the probability of B given A.

Used by Edexcel

Specification 3p.07, 3p.08, 3p.09 · Paper 1, Paper 2

The probability of an event when another event is known to have occurred. $P(B\mid A)$ means the probability of $B$ given $A$ .

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Learn the conditional probability formula. Convert percentages and fractions into a consistent form before substituting.

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Conditional probability is probability calculated when some information is already known.

The probability of an event given information that another event has occurred. For example, $P(B|A)$ means the probability of $B$ given $A$ .