1. 3.3 The Addition Rule Important Concepts Mutually Exclusive Events
Using the Addition Rule to Find “or” Probabilities

2. 3.3 The Addition Rule Card Draw Problem:
Select one card from a deck of 52.
What is the probability the card is a 5 or is a King?
What is the probability the card is a 10 or a red card?
We can calculate “or” probabilities using what we learned in section Sometimes, it is easier to use the Addition Rule.

3. 3.3 The Addition Rule
If we have an “or” probability, we need to ask ourselves an important question:
Can the events in question occur simultaneously?
If they cannot occur at the same time, we say the events are mutually exclusive. If they can, we say they are not mutually exclusive.
#10 p. 162
#12 p. 162

4. 3.3 The Addition Rule The Addition Rule
P( A or B ) = P( A ) + P( B ) – P( A and B )
If A and B are mutually exclusive events, then the Addition Rule becomes
P( A or B ) = P( A ) + P( B )
#18 p. 163 (Die Toss)
#24 p. 164 (Junk Food Tax)