Goals
Notes
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Mutually Exclusive Events (Venn diagrams are useful!)
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The Addition Rule
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A Summary of Rules for Probabilities.
Mutually Exclusive Events
Notes
Use Venn diagrams to visualize events.
Probability Experiment: Select a Tablet Owner
Event A: ”Owns an iPad” Event B: ”Owns a Kindle”
Owns a Tablet
A
B
Events A and B overlap and are not mutually exclusive.
Mutually Exclusive Events
Notes
Mutually Exclusive Events do not overlap. These events have no
common possilbe outcomes.
Probability Experiment: ”Roll a six-sided die”
Event A: ”Roll a two.” Event B: ”Roll greater than three.”
Rolls a six-sided die
4,5,6
2
1,3
The Addition Rule
Notes
The probability of the event ”A and B” had the multiplication rule:
The Multiplication Rule
P(A and B) = P(A) · P(B|A)
The probability of the event ”A or B” uses the addition rule:
The Addition Rule
P(A or B) = P(A) + P(B) − P(A and B)
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Why do we need to subtract P(A and B)?
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Can we use a special addition rule like we had with the special
Multiplication Rule?
Summary of probability rules
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Notes
0 ≤ P(A) ≤ 1.
P(A) + P(A0 ) = 1.
P(A and B) = P(A) · P(B|A).
P(A and B) = P(A) · P(B) if A and B are independent.
P(A or B) = P(A) + P(B) − P(A and B).
P(A or B) = P(A) + P(B) if A and B are mutually exclusive.
Assignment
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§3.3: #14, #17, #20, #24, #27, #28,
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Read 3.4
Suggested Exercises: #1, #2, #7, #8, #9, #11
Notes