Download 8.7-Probability

Lesson 8.7
Page 645-648
#1-29 (ODD), 33, 35, 41, 43, 47, 49,
53-57 (ODD)
Pick up the handout on the table.
Probability
Objective
Students will know how to find the probabilities of events
and their complements.
Probability - is a number between 0 and 1 that
indicates the likelihood the event will
occur.
* An event that is certain to occur has a probability of 1.
* An event that cannot occur has a probability of 0.
Sample Space - the set of all possible outcomes.
Event - any subcollection of a sample space.
Compound Event - the union or intersection of two
events.
All the outcomes for either of two events A and
B, form the union of A and B.
Only the outcomes shared by both A and B form
the intersection of A and B.
If there are no outcomes
in the intersection of A
and B, then A and B are
mutually exclusive
events.
Probability of Compound Events
If A and B are two events, then the probability of A
or B is :
PA or B PA  PB  PA and B
If A and B are mutually exclusive, then the
probability of A or B is :
PA or B PA  PB
Dependent Events - the occurrence of one event
affects the occurrence of the
other.
The probability that B will occur given that A
has occurred is called the conditional
probability of B given A.
PB A

Probability of Dependent Events
If A and B are dependent events, then the
probability that both A and B occur is :
PA and B  PA  PB A

Independent Events - the occurrence of one event
has no effect on the occurrence
of the other event.
Probability of Independent Events
If A and B are independent events, then the
probability that both A and B occur is :
PA and B  PA  PB

Complement - consists of all outcomes that are
not in A.
Event A’
“A prime”
What is the probability that an event is certain to occur?
Probability of the Complement of an Event
The probability of the complement of A is
P(A’) = 1 - P(A).