Why? Because P(A n B) does not equal zero. Because P(B | A) equals P(B). Because P(A n B) equals 0. Because P(B | A) does not equal P(B). What does this mean? Event A occurring does not affect the likelyhood of event B ocurring. Events A and B cannot happen at the same time. Event A occurring affects the likelihood of event B occurring Events A and B can happen at the same time