... United States.

The scatterplot and fitted line show negative association. Heavier cars on average get fewer miles per gallon. The linear pattern attributes about 60% of the variation in mileage to differences in weight (r2 = 0.634), and the standard deviation of the residuals is se = 2.51 MPG.

Let’s interpret the estimated intercept and slope. The equation of the line is

Estimated Combined MPG=38.24.23 Weight (1,000 lbs)

It would be naïve to interpret b0 as telling us that a “weightless car” would get 38.2 MPG on average; we can instead think of b0 as the mileage attainable before accounting for moving the mass of a car. The intercept is a reminder that cars burn fuel regardless of their weight to power the air conditioning and electronics. No matter ...

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