1. Mutually Exclusive Events

2. Hipster Venn Diagram

6. What if…
We wanted the probability of event A happening OR event B happening?
To answer this we first must define a few things

7. Mutually exclusive events are…
two events that have NO COMMON ELEMENTS (they cannot both occur at the same time).
Examples:
Drawing an ace, or a face card
Rolling doubles, or a total of 7 on two dice
Key terms: or, no common element

8. Mutually Exclusive Events (A Visual)

9. To find P(A U B) for two mutually exclusive events A and B…
you ADD the probabilities
P(AUB) = P(A) + P(B)

10. Mutually Exclusive Example
A pair of dice is rolled. What is the probability that the sum of the numbers rolled is either 7 OR 11?

11. Non-Mutually Exclusive Events
Two events, A and B are Not Mutually Exclusive, if they share a common element.
Examples:
Drawing a king or a face card
Rolling doubles or a total of 10 with some dice

12. Non-Mutually Exclusive Events
The probability P(AUB) of non-mutually exclusive events is given by…
P(AUB) = P(A) + P(B) – P(A∩B)
But why subtract the intersection?

13. Non-Mutually Exclusive Events (A Visual)
The intersection is added TWICE because of the overlap. So we subtract it ONCE.
P(AUB) = P(A) + P(B) – P(A∩B)

14. Non-Mutually Exclusive Example
A pair of dice is rolled. What is the probability doubles are rolled OR a total of 10 is rolled?

15. Homework
P. 42 #1 - 7, 9a, 10, 11, 14