A lawn care company tried to predict the demand for its service by zip code, using the housing density in the zip code area as a predictor. The owners obtained the number of houses and the geographic size of each zip code and calculated their sales per thousand homes and number of homes per acre.

a. Obtain the correlation between the two variables. What does its sign mean?
b. Obtain a prediction equation with sales as the dependent variable and density as the independent variable. Interpret the intercept (yes, we know the interpretation will be a bit strange) and the slope numbers.
c. Obtain a value for the residual standard deviation. What does this number indicate about the accuracy of prediction?

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Sales S4 2 54 62 72 83 115 90 66 60 100 78 152 87 54 82 Density 6.5 4.6 55 46 4.2 4.3 2.3 35 32 84 34 4.0 20 3.2 6.7 3.0 Sales 59 183 171 96 134 79 94 82 66 62 45 69 65 81 94 117 Density 5.7 13 13 3.0 2.2 43 26 3.0 43 78 94 42 5.9 6.2 2.8 24