# Fan Appreciation Night, Part 2

Key Terms:

Intersection
Union
Addition Rule

## Create and Analyze

The is known as finding the probability of the intersection of A and B, and may also be written as .  Let’s explore what finding means for mutually inclusive events.  Since mutually inclusive events can occur at the same time, the situation can be represented with a Venn diagram:

To find the probability of the intersection of A or B, , we cannot simply find the , because the two probabilities overlap with the section .  This section would be counted twice.

Since the , the union of A and B, is counted twice, you would need to subtract one of these sections to find the .  So, when events are mutually inclusive, you apply the Addition Rule,

Let’s explore how to find the probability of winning a t-shirt or a hat.