HSS-CP.A.3

Understand the conditional probability of $A$ given $B$ as $P(\mbox{$A$ and $B$})/P(B)$, and interpret independence of $A$ and $B$ as saying that the conditional probability of $A$ given $B$ is the same as the probability of $A$, and the conditional probability of $B$ given $A$ is the same as the probability of $B$.