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Conditional Probability

High School

Definition

Conditional probability P(A|B) is the probability of event A occurring given that event B has occurred.

P(A|B) = (P(A ∩ B))/(P(B))

Definition of conditional probability

P(A ∩ B) = P(A|B) · P(B)

Multiplication rule

P(A|B) = (P(B|A) · P(A))/(P(B))

Bayes' theorem

Example 1

From 52 cards, given that a heart was drawn, find P(it's a King).

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