Download 8-7 Fitting to a Normal Distribution

8­7 Fitting to a Normal Distribution­ period 1.notebook
April 08, 2015
Bellwork 4-8-15
Find the mean and standard deviation of each data set.
1. {2, 10, 5, 3}
2. {30, 30, 60}
3. {2, 2, 2, 2,2}
4. Determine which data set has the greater standard deviation
without calculating it. Explain. Set A: {73, 120, 54, 81, 66}
Set B: {83, 95, 106, 99, 82}.
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8­7 Fitting to a Normal Distribution­ period 1.notebook
April 08, 2015
Objectives
Use tables to estimate areas under normal curves.
Recognize data sets that are not normal.
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8­7 Fitting to a Normal Distribution­ period 1.notebook
April 08, 2015
Vocabulary
standard normal value
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8­7 Fitting to a Normal Distribution­ period 1.notebook
April 08, 2015
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8­7 Fitting to a Normal Distribution­ period 1.notebook
April 08, 2015
Example 1: Finding Joint and Marginal Relative
Frequencies
Jamie can drive her car an average of 432 miles per tank of gas,
with a standard deviation of 36 miles. Use the graph to estimate
the probability that Jamie will be able to drive more
than 450 miles on her next tank of gas.
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8­7 Fitting to a Normal Distribution­ period 1.notebook
April 08, 2015
Example 1 : Continued
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8­7 Fitting to a Normal Distribution­ period 1.notebook
April 08, 2015
Check It Out! Example 1
Estimate the probability that Jamie will be able to drive less than
400 miles on her next tank of gas?
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8­7 Fitting to a Normal Distribution­ period 1.notebook
April 08, 2015
Example 2: Using Standard Normal Values
Scores on a test are normally distributed with a mean of 160 and
a standard deviation of 12.
A. Estimate the probability that a randomly selected student
scored less than 148.
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8­7 Fitting to a Normal Distribution­ period 1.notebook
April 08, 2015
Example 2: Using Standard Normal Values continued
B. Estimate the probability that a randomly selected student
scored between 154 and 184.
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8­7 Fitting to a Normal Distribution­ period 1.notebook
April 08, 2015
Check It Out! Example 2
Scores on a test are normally distributed with a mean of 142 and
a standard deviation of 18. Estimate the probability of scoring
above 106.
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8­7 Fitting to a Normal Distribution­ period 1.notebook
April 08, 2015
Example 3: Determining Whether Data May Be Normally
Distributed
The lengths of the 20 snakes at a zoo, in inches, are shown in the
table. The mean is 34.1 inches and the standard deviation is 10.5
inches. Does the data appear to be normally distributed?
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8­7 Fitting to a Normal Distribution­ period 1.notebook
April 08, 2015
Example 3: Continued
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8­7 Fitting to a Normal Distribution­ period 1.notebook
April 08, 2015
Check It Out! Example 3
A random sample of salaries at a company is shown. If the mean is
$37,000 and the standard deviation is $16,000, does the data
appear to be normally distributed?
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8­7 Fitting to a Normal Distribution­ period 1.notebook
April 08, 2015
Homework: Worksheet 8-7 Practice A
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