A US consumer lobby wishes to develop a model to predict gasoline usage, as measured by miles per gallon, based on the weight of the car in pounds. The Excel data file AUTO.xls (contained in a folder under the CML Quizzes tab)contains data on this for fifty recent models. Use Excel Data Analysis to estimate a linear model for the relationship, a 95% confidence interval for the slope coefficient and a residual plot. State all numerical answers below correct to four decimal places using the Excel output results.

1. the intercept

2. the slope coefficient,

3. the standard error of the estimate

4. Using this model, predict the gasoline usage for a car weighing 1200 pounds. Use all decimal places in your calculation by selecting and using the values ofb₀andb₁in the output generated by Excel.

5. Does the prediction involve extrapolating the relationship? Type yes or no.

State the

6. lower boundand 7. upper boundfor the 95% confidence interval for the slope coefficient.

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