9-2 Experimental Probability
Warm Up
Problem of the Day
Lesson Presentation
Lesson Quizzes
9-2 Experimental Probability
Warm Up
1. A jar contains 6 red, 8 blue, and 10 white
marbles. Would you be more likely to pull out a red
or a blue marble? blue
Determine if the event is impossible, unlikely,
as likely as not, likely, or certain.
2. Attendance at a city council meeting is at 100%.
Mr. Lloyd is a council member. How likely is it that
Mr. Lloyd is at the meeting? certain
9-2 Experimental Probability
Problem of the Day
The probability of Liana making a free
. If she made 24 of her free
throw was 2
3
throws, how many did she miss?
12
9-2 Experimental Probability
Sunshine State Standards
MA.7.P.7.2 Determine, compare, and make
predictions based on
experimental…probability…
9-2 Experimental Probability
Vocabulary
experimental probability
9-2 Experimental Probability
Experimental probability is one way of estimating
the probability of an event. The experimental
probability of an event is found by comparing
the number of times an event occurs to the total
number of trials. The more trials you have, the
more accurate the estimate is likely to be.
9-2 Experimental Probability
9-2 Experimental Probability
Additional Example 1: Sports Application
During skating practice, Sasha landed 7 out
of 12 jumps. What is the experimental
probability that she will land her next jump?
P(event)  number of times an event occurs
total number of trials
number of jumps landed
P(jumps landed)  number
of jumps attempted
= 7 Substitute data from the experiment.
12
The experimental probability that Sasha will land her
next jump is 7 .
12
9-2 Experimental Probability
Writing Math
“P(event)” represents the probability that an event
will occur. For example, the probability of a flipped
coin landing heads up could be written as “P(heads).”
9-2 Experimental Probability
Check It Out: Example 1A
During basketball practice, Martha made 9 out of
10 free throws. What is the experimental
probability that she will make her next attempt?
Write your answer as a fraction, a decimal, and a
percent.
P(event) = number of times event occurs
number of trials
P(makes shots) = number of times free throws were made
total number of free throws
9 = 0.9 = 90%
P(makes shots) = 10
9-2 Experimental Probability
Check It Out: Example 1B
Emmanuel wins 12 out of 15 of his chess
matches. What is the experimental probability
that he will win his next game? Write your
answer as a fraction, a decimal, and a percent.
P(event) =
P(win) =
P(win) =
number of times event occurs
number of trials
number of wins
total number of games
12 = 4 = 0.8 = 80%
15
5
9-2 Experimental Probability
Additional Example 2A: Application
Students have checked out 55 books from the
library. Of these, 32 books are fiction.
What is the experimental probability that
the next book checked out will be fiction?
number of fiction books checked out
P(fiction)  total number of books checked out
32
 55
Substitute data.
The experimental probability that the next book
checked out will be fiction is approximately 32.
55
9-2 Experimental Probability
Additional Example 2B: Application
What is the experimental probability that
the next book checked out will be nonfiction?
P(fiction) + P(nonfiction) = 1
32
55
– 32
55
+
P(nonfiction) = 1
–
32
55
P(nonfiction) = 23
55
Use the complement.
Substitute.
Subtract 32
55 from
both sides.
Simplify.
The experimental probability that the next book checked
out will be nonfiction is approximately 23.
55
9-2 Experimental Probability
Check It Out: Example 2A
For the past two weeks, Kyle kept track of
how long he practiced guitar each day. His
results are shown in the tables.
Week 1
Sun
Mon
Tues
Wed
Thur
Fri
Sat
Time (in min)
45
35
40
50
55
45
45
Week 2
Sun
Mon
Tues
Wed
Thur
Fri
Sat
Time (in min)
65
45
45
40
60
55
60
9-2 Experimental Probability
Check It Out: Example 2A Continued
What is the experimental probability that Kyle
will practice for 50 minutes or more?
of times events occurs
P(event) = numbernumber
of trials
of days of practice > 50 min
P(50 or more) = number
total number of days
P(50 or more) =
6 = 3
7
14
9-2 Experimental Probability
Check It Out: Example 2B
What is the experimental probability that Kyle
will practice less than 50 minutes?
P(50 or more) + P(less than 50) = 1
3 + P(less than 50) = 1
7
4
=
P(less than 50) = 1 3
7 7
9-2 Experimental Probability
Lesson Quizzes
Standard Lesson Quiz
Lesson Quiz for Student Response Systems
9-2 Experimental Probability
Lesson Quiz
1. In a soccer shoot-out, Bryan made 4 out of 9
4
goals. What is the experimental probability that he 9
will make the next shot?
2. It has rained on the last 2 out of 10 Fourth of
July parades in Swanton.
A. What is the experimental probability that it will 1
5
rain on the Fourth of July parade this year?
B. What is the experimental probability that it will
not rain on the Fourth of July parade this year?
4
5
9-2 Experimental Probability
Lesson Quiz for Student Response Systems
1. During a shot put practice session, Greg crossed
the 70-foot mark in 15 out of 21 attempts. What is
the experimental probability that he will cross the
70-foot mark in his next attempt?
A. 2
7
5
B. 7
C. 6
7
D. 7
5
9-2 Experimental Probability
Lesson Quiz for Student Response Systems
2. Simon is practicing basketball. He made 33 of
42 free throws he attempted. What is the
experimental probability that we will make his next
free throw?
9
14
11
B. 42
C. 11
14
A.
D. 14
11
9-2 Experimental Probability
Lesson Quiz for Student Response Systems
3. Rachel found that 20 out of 48 cars that entered
a parking lot were red. What is the experimental
probability that the next car that comes in is red?
What is the experimental probability that the next
car that comes in is not red?
A.
B.
C.
D.