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Probability Calculator

P(A∩B), P(A∪B), and conditional probabilities via Bayes — with Venn diagram.

Inputs

P(A)

0–1

P(B)

0–1

Relationship

P(A∩B) = P(A)·P(B) — knowledge of A does not affect P(B)

Results

P(A ∩ B)—

P(A ∪ B)—

P(A | B) Bayes—

P(B | A) Bayes—

P(A∩B) = P(A)·P(B) · P(A|B) = P(A∩B)/P(B)

Conditional probabilities require P(denominator) > 0.
P(A|B) answers: "given B occurred, what is P(A)?"