## Thinking Mathematically (6th Edition)

$\frac{1}{3}$
The probability of event B, assuming that the event A has already occurred, is called the conditional probability of B, given A. This probability is denoted by P(B|A). E: A yellow disk, given that the number selected is at most 3. A: There are 3 disks given that the number selected is at most 3. B: There is only 1 way in which a yellow disk is selected from the 3 disks. P(B|A) = $\frac{1}{3}$