Warm Up

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Preview
Warm Up
California Standards
Lesson Presentation
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Warm Up Write each fraction in simplest
form. 1. 2. 3. 4.
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64
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(No Transcript)
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Vocabulary
experiment trial outcome sample
space event probability
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An experiment is an activity in which results are
observed. Each observation is called a trial, and
each result is called an outcome. The sample
space is the set of all possible outcomes of an
experiment.

• Experiment Sample Space
• flipping a coin heads, tails
• rolling a number cube 1, 2, 3, 4, 5, 6

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• An event is any set of one or more outcomes. The
  probability of an event is a number from 0 (or
  0) to 1 (or 100) that tells you how likely the
  event is to happen. You can write probability as
  a fraction, a decimal, or a percent.
• A probability of 0 means the event is
  impossible, or can never happen.
• A probability of 1 means the event is certain,
  or will always happen.
• The probabilities of all the outcomes in the
  sample space add up to 1.

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Never Happens about Always happens
half the time happens
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0
0 0.25 0.5
0.75 1 0 25
50 75 100
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Additional Example 1A Finding Probabilities of
Outcomes in a Sample Space
Give the probability for each outcome.
The basketball team has a 70 chance of winning.
P(win) 70 0.7. P(lose) 1 0.7 0.3, or
30
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Additional Example 1B Finding Probabilities of
Outcomes in a Sample Space
Give the probability for each outcome.
3 8
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Additional Example 1B Continued
Check The probabilities of all the outcomes must
add to 1.
?
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Check It Out! Example 1A
Give the probability for each outcome.
The polo team has a 50 chance of winning.
P(win) 50 0.5. P(lose) 1 0.5 0.5, or
50.
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Check It Out! Example 1B
Give the probability for each outcome.
Outcome Teal Red Orange
Probability
3 8
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Check It Out! Example 1B Continued
Check The probabilities of all the outcomes must
add to 1.
?
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To find the probability of an event, add the
probabilities of all the outcomes included in the
event.
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Additional Example 2A Finding Probabilities of
Events
A quiz contains 5 true-false questions. Suppose
you guess randomly on every question. The table
below gives the probability of each score.
What is the probability of guessing 3 or more
correct?
The event three or more correct consists of the
outcomes 3, 4, and 5.
P(3 or more correct) 0.313 0.156 0.031
0.5, or 50.
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Additional Example 2B Finding Probabilities of
Events
A quiz contains 5 true-false questions. Suppose
you guess randomly on every question. The table
below gives the probability of each score.
What is the probability of guessing fewer than 2
correct?
The event fewer than 2 correct consists of the
outcomes 0 and 1.
P(fewer than 2 correct) 0.031 0.156
0.187, or 18.7.
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Check It Out! Example 2A
A quiz contains 5 true-false questions. Suppose
you guess randomly on every question. The table
below gives the probability of each score.
What is the probability of guessing 2 or more
correct?
The event two or more correct consists of the
outcomes 2, 3, 4, and 5.
P(2 or more) 0.313 0.313 0.156 0.031
0.813, or 81.3.
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Check It Out! Example 2B
A quiz contains 5 true-false questions. Suppose
you guess randomly on every question. The table
below gives the probability of each score.
What is the probability of guessing fewer than 3
correct?
The event fewer than 3 consists of the outcomes
0, 1, and 2.
P(fewer than 3) 0.031 0.156 0.313 0.5, or
50.
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Lesson Quiz
Use the table to find the probability of each
event. 1. 1 or 2 occurring 2. 3 not
occurring 3. 2, 3, or 4 occurring
0.351
0.874
0.794