Experimental Probability

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10-5
Experimental Probability
Warm Up
Lesson Presentation
Lesson Quiz
Holt Algebra 1
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Warm Up Part I Write the equivalent percent. 1.
2. 3.
4. Write the equivalent fraction.
25
30
16
20
5.
6.
50
10
7.
8.
35
40
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Warm Up Part II Write the equivalent decimal. 9.
18 10. 50 11.
12.
0.18
0.5
0.9
0.2
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Objectives
Determine the experimental probability of an
event. Use experimental probability to make
predictions.
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Vocabulary
experiment experimental probability trial
prediction outcome sample
space event probability
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An experiment is an activity involving chance.
Each repetition or observation of an experiment
is a trial, and each possible result is an
outcome. The sample space of an experiment is the
set of all possible outcomes.
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Example 1 Identifying Sample Spaces and Outcomes
Identify the sample space and the outcome shown
for each experiment.
A. Rolling a number cube
Sample space1, 2, 3, 4, 5, 6
Outcome shown 4
B. Spinning a spinner
Sample spacered, green, orange, purple
Outcome shown green
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Check It Out! Example 1
Identify the sample space and the outcome shown
for the experiment rolling a number cube.
Sample space 1, 2, 3, 4, 5, 6
Outcome shown 3
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An event is an outcome or set of outcomes in an
experiment. Probability is the measure of how
likely an event is to occur. Probabilities are
written as fractions or decimals from 0 to 1, or
as percents from 0 to 100.
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As likely as not
Impossible
Certain
Unlikely
Likely
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Example 2 Estimating the Likelihood of an Event
Write impossible, unlikely, as likely as not,
likely, or certain to describe each event.
A. A shoe selected from a pair of shoes fits the
right foot.
as likely as not
B. Katrina correctly guesses the last digit of a
phone number.
unlikely
C. Max pulls a green marble from a bag of all
green marbles.
certain
D. A randomly selected month contains the letter
R.
likely
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Check It Out! Example 2
Write impossible, unlikely, as likely as not,
likely, or certain to describe the event
Anthony rolls a number less than 7 on a
standard number cube.
The highest number on a standard number cube is
6. Thus it is certain the number will be less
than 7.
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You can estimate the probability of an event by
performing an experiment. The experimental
probability of an event is the ratio of the
number of times the event occurs to the number of
trials. The more trials performed, the more
accurate the estimate will be.
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Example 3A Finding Experimental Probability
An experiment consists of spinning a spinner. Use
the results in the table to find the experimental
probability of the event.
Outcome Frequency
Green 15
Orange 10
Purple 8
Pink 7
Spinner lands on orange
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Example 3B Finding Experimental Probability
An experiment consists of spinning a spinner. Use
the results in the table to find the experimental
probability of the event.
Outcome Frequency
Green 15
Orange 10
Purple 8
Pink 7
Spinner does not land on green
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Check It Out! Example 3a
An experiment consists of spinning a spinner. Use
the results in the table to find the experimental
probability of each event.
Outcome Frequency
Red 7
Blue 8
Green 5
Spinner lands on red
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Check It Out! Example 3b
An experiment consists of spinning a spinner. Use
the results in the table to find the experimental
probability of each event.
Outcome Frequency
Red 7
Blue 8
Green 5
Spinner does not land on red
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You can use experimental probability to make
predictions. A prediction is an estimate or guess
about something that has not yet happened.
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Example 4A Quality Control Application
A manufacturer inspects 500 strollers and finds
that 498 have no defects.
What is the experimental probability that a
stroller chosen at random has no defects?
Find the experimental probability that a stroller
has no defects.
99.6
The experimental probability that a stroller has
no defects is 99.6.
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Example 4B Manufacturing Application
A manufacturer inspects 500 strollers and finds
that 498 have no defects.
The manufacturer shipped 3500 strollers to a
distribution center. Predict the number of
strollers that are likely to have no defects.
Find 99.6 of 3500.
0.996(3500) 3486
The prediction is that 3486 strollers will have
no defects.
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Check It Out! Example 4a
A manufacturer inspects 1500 electric toothbrush
motors and finds 1497 have no defects.
What is the experimental probability that a motor
chosen at random will have no defects?
Find the experimental probability that a motor
has no defects.
99.8
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Check It Out! Example 4b
A manufacturer inspects 1500 electric toothbrush
motors and finds 1497 have no defects.
There are 35,000 motors in a warehouse. Predict
the number of motors that are likely to have no
defects.
Find 99.8 of 35,000.
0.998(35000) 34930
The prediction is that 34,930 motors will have no
defects.
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Lesson Quiz Part I
1. Identify the sample space and the outcome
shown for selecting a marble.
Sample space red, green, yellow
Outcome shown red
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Lesson Quiz Part II
2. An experiment consists of spinning a spinner.
Use the results in the table to find the
experimental probability of landing on blue.
Outcome Frequency
Red 9
Blue 6
Yellow 5
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Lesson Quiz Part III
3. The neighbors dog barked at Tana the last 4
out of 5 times she walked by their house.
a. What is the experimental probability that the
dog barks at Tana when she walks past the house?
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b. Predict the number of times the dog will bark
at Tana if she walks past the house 45 times.
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