100 people were surveyed for their favorite fast-food restaurant.
McDonald’s
Burger King
Wendy’s
Male
20
15
10
Female
20
10
25
1. What is the probability that a person likes Wendy’s?
7/20
2. What is the probability that a person is male who likes Burger
King?
3/20
3. What is the probability that a person is likes McDonald’s or
Burger King?
13/20
Probabilities of Compound Events
UNIT QUESTION: How do you use
probability to make plans and predict
for the future?
Standard: MM1D1-3
Today’s Question:
When do I add or multiply when
solving compound probabilities?
Standard: MM1D2.a,b.
Lesson 6.4 p. 351
A compound event combines two or more events,
using the word and or the word or.
If two or more events cannot occur at the same time
they are termed mutually exclusive (disjoint).
They have no common outcomes.
Overlapping events have at least one common
outcome.
Two events are independent if the occurrence of one
event has no effect on the other
Two events are dependent if the occurrence of one
event affects the outcome of the other
Mutually Exclusive Events
The probability is found by summing the individual
probabilities of the events:
P(A or B) = P(A) + P(B)
A Venn diagram is used to show mutually exclusive events.
Mutually Exclusive Events
Example 1:
Find the probability that a girl’s favorite department store is
0.45
Macy’s or Nordstrom.
Find the probability that a girl’s favorite store is not JC
Penney.
0.90
Macy’s
Saks
Nordstrom
JC Penney
Bloomingdale’s
0.25
0.20
0.20
0.10
0.25
Mutually Exclusive Events
Example 2:
When rolling two dice, what is probability that your sum will
be 4 or 5?
7/36
Mutually Exclusive Events
Example 3:
What is the probability of picking a queen or an ace from a
deck of cards
2/13
Overlapping Events
Probability that overlapping events A and B or both
will occur expressed as:
P(M or E) = P(M) + P(E) - P(ME)
Overlapping Events
Example 1:
4/13
Find the probability of picking a king or a club in a deck of
cards.
Overlapping Events
Example 2:
Find the probability of picking a female or a person from
Tennessee out of the 31 committee members.
Fem
Male
TN
8
4
AL
6
3
GA
7
3
21 12 8 25
  
31 31 31 31
Overlapping Events
Example 3:
When rolling 2 dice, what is the probability of getting an
even sum or a number greater than 10?
18 3 1 20
 

36 36 36 36
Independent Events
• Two events A and B, are independent if A occurs
& does not affect the probability of B occurring.
• Examples- Landing on heads from two different
coins, rolling a 4 on a die, then rolling a 3 on a
second roll of the die.
• Probability of A and B occurring:
P(A and B) = P(A) ∙ P(B)
Experiment 1
• A jar contains three red, five green, two
blue and six yellow marbles. A marble is
chosen at random from the jar. After
replacing it, a second marble is chosen.
What is the probability of choosing a green
and a yellow marble?
 P (green) = 5/16
 P (yellow) = 6/16
 P (green and yellow) = P (green) ∙ P (yellow)
= 15 / 128
Dependent Events
• Two events A and B, are dependent if A occurs &
affects the probability of B occurring.
• Examples- Picking a blue marble and then picking
another blue marble if I don’t replace the first one.
• Probability of A and B occurring:
P(A and B)=P(A) ∙ P(B given A)
Experiment 2
• A random sample of parts coming off a
machine is done by an inspector. He found
that 5 out of 100 parts are bad on average.
If he were to do a new sample, what is the
probability that he picks a bad part and then
picks another bad part if he doesn’t replace
the first?
P (bad) = 5/100
 P (bad given bad) = 4/99
 P (bad and then bad) = 1/495

Experiment 3
• A jar contains three red, five green, two
blue and six yellow marbles. A marble is
chosen at random from the jar. A second
marble is chosen. What is the probability of
choosing a green and a yellow marble if the
first marble is not replaced?
 P (green) = 5/16
 P (yellow) = 6/15
 P (green and yellow) = P (green) ∙ P (yellow)
= 30 / 240 = 1/8
Experiment 4
• A jar contains three red, five green, two
blue and six yellow marbles. A marble is
chosen at random from the jar. A second
marble is chosen. What is the probability of
choosing a green marble both times if the
first marble is not replaced?
 P (green) = 5/16
 P (green) = 4/15
 P (green and green) = P (green) ∙ P (green)
= 20 / 240 = 1/12
P(A or B) = P(A) + P(B)
-Drawing a king or a queen
-Selecting a male or a female
-Selecting a blue or a red marble
P(A and B) = P(A) ∙ P(B)
P(A or B) = P(A) + P(B) - P(overlap)
-Drawing a king or a diamond
-rolling an even sum or a sum
greater than 10 on two dice
-Selecting a female from Georgia
or a female from Atlanta
P(A and B) = P(A) ∙ P(B given A)
WITH REPLACEMNT:
WITHOUT REPLACEMENT:
-Drawing a king and a queen
-Drawing a king and a queen
-Selecting a male and a female
-Selecting a male and a female
-Selecting a blue and a red marble
-Selecting a blue and a red marble
Classwork
• Get your WORKBOOK and do
p. 369, #1-11 all
Homework
Pg. 353 1-8 all