Question

If A and B are events and \[P(B) \neq 0\], which expression gives \[P(A \mid B)\]?

Options

• \[P(A \mid B)=1-P(B)\]

• \[P(A \mid B)=\frac{P(A\cap B)}{P(B)}\]

• \[P(A \mid B)=\frac{P(A\cap B)}{P(A)}\]

• \[P(A \mid B)=P(A)+P(B)\]

Answer 1

The denominator is \[P(B)\] because B is the event already known to have occurred. The numerator \[P(A\cap B)\] contains outcomes common to both events.