Download Date: Section 4.3 Elementary Statistics Digital Notes Addition Rule

Date:
Section 4.3
Elementary Statistics
Digital Notes
Addition Rule
Definition - P(A or B) is
Example – What is the probability of either rolling an even number OR rolling at least a 4?
Definition – A Venn Diagram is
Example -
Addition Rule
Formula: P(A or B) = P(A) + P(B) – P(A and B)
Using slightly more mathematical symbols:
P  A∪ B= P A P  B− P  A∩ B
Example – 20. Use the polygraph test data given in Table 4-1. If one of the subjects is randomly
selected, find the probability that the subject had a negative test result or lied.
Definition – Two events are mutually exclusive if
Example – The events of rolling an even number or rolling at least a 4 are NOT mutually exclusive.
Example – The events of rolling an even number or rolling an odd number ARE mutually exclusive.
Venn Diagram of Two Mutually Exclusive Events
Rule – If A and B are mutually exclusive, then P(A or B) = P(A) + P(B).
Example – What is the probability of getting a hearts or diamonds if you are randomly dealt one card
from a standard 52-card deck?
Complementary Events
Formula:
P  A=1− P  A 
Example Let A = rolling less than a 5
Then
A =
P  A=?
Example – What is the probability of NOT getting a face card if you are randomly dealt one card from
a standard 52-card deck?
Homework → 4.3 – 5, 6, 8, 9, 12, 14, 15, 17, 19, 21, 24, 26, 27, 30, 33, 34, 35, 36, 37