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Is everything related with a linear trend?2.5 Scatter Plots and Lines of Best Fit

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http://tinyurl.com/c7ztkh7

http://tinyurl.com/buwgtg7

Real Life Examples of Scatter Plots

http://tinyurl.com/cfzqeea

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Is the best fit always linear?

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Postive Correlation Negative Correlation

No Correlation

Correlation

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Correlation

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Line of Best Fit - a line that best represents the data on a scatter plot.

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County Incidence of Exposure Cancer Death Rate

Clatsop 8.3 210

Columbia 6.4 178

Gilliam 3.4 130

Hood River 3.8 162

Morrow 2.6 130

Portland 11.6 208

Sherman 1.3 114

Umatilla 2.5 147

Wasco 1.6 138

Example 1: There was a toxic waste spill in Oregon and scientists are trying to determine if the amount of exposure can be linked to death rates from cancer by county. Below is the data.

a) Given that the incidence of exposure is 15, find the cancer death rate.

b) Given that the cancer death rate is 300, how much incidence of exposure was there?

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Age 4 5 6 7 8 9 11 12 13 15 16 18 20

Price 6500 7000 5500 5000 4750 3200 3000 2250 2000 1750 1500 1000 750

Example 2: Below are statistics for the price of your car based on its age.

b) Find the line of best fit.

a) Is there a correlation? If so, what kind?

c) If your car is worth $200, how old is it?

d) If your car is 10 years old, what will its value be? (How much couldyou sell your car for when it is 10 years old?)

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