Question

For any two events, which formula gives the probability of their union?

Options

• \(P(A \cup B) = P(A) + P(B) - P(A \cap B)\)

• \(P(A \cup B) = P(A)P(B)\)

• \(P(A \cup B) = P(A) + P(B)\)

• \(P(A \cup B) = P(A) - P(B) + P(A \cap B)\)

Answer 1

Adding \(P(A)\) and \(P(B)\) counts the outcomes in \(A \cap B\) twice. Subtracting \(P(A \cap B)\) gives the probability of the union.