## Precalculus (6th Edition) Blitzer

If the occurrence of one event has no effect on the probability of another event, the events are said to be independent events. For such events, $P\left( A\ \text{ and }\ B \right)=$ $P\left( A \right)\cdot P\left( B \right)$.
We know that two events are independent events if the occurrence of either of them has no effect on the probability of the other; $P\left( A\ \text{ and }\ B \right)=P\left( A \right)\cdot P\left( B \right)$