Chapter 11 - Counting Methods and Probability Theory - 11.7 Events Involving And; Conditional Probability - Exercise Set 11.7 - Page 747: 53

$\frac{3}{4}$

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 red disk, given that an odd number is selected. A: There are 4 odd numbered disks. B: There are 3 disks that have odd numbers and are red. Thus, we have: P(B|A) = $\frac{3}{4}$