Is it Normal

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Is it Normal?
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Many different types of data have very similar
distributions
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Test Scores
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Womens Heights
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Body Temperatures
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Normal Random Numbers
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Normal Distribution
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68 95 99.7 Rule
Mean 0 Standard deviation 1
Standard Normal Distribution
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Normal Distribution
Womens Heights
Mean 64.5 inches Std dev 2.5 inches
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Example
Guzzlers. Environmental Protection Agency (EPA)
fuel economy estimates for automobile models
tested recently predicted a mean of 24.8 mpg and
a standard deviation 6.2 mpg for highway driving.
Assume that a Normal model can be applied.

• Draw the model for auto fuel economy. Clearly
  label it, showing what the 68-95-99.7 Rule
  predicts about miles per gallon.
• In what interval would you expect the central 68
  of autos to be found.
• About what percent of autos should get more than
  31 mpg?
• About what percent of cars should get between 31
  and 37 mpg?
• Describe the gas mileage of the worst 2.5 of all
  cars.