Chapter 8, Problem 40E

Speed How does the speed at which you drive affect your fuel economy? To find out, researchers drove a compact car for 200 miles at speeds ranging from 35 to 75 miles per hour. From their data, they created the model   $\widehat{fuelEfficiency}=32-0.1$ Speed and created this residual plot:

1. a) Interpret the slope of this line in context.
2. b) Explain why it’s silly to attach any meaning to the y-intercept.
3. c) When this model predicts high Fuel Efficiency, what can you say about those predictions?
4. d) What Fuel Efficiency does the model predict when the car is driven at 50 mph?
5. e) What was the actual Fuel Efficiency when the car was driven at 45 mph?
6. f) Do you think there appears to be a strong association between Speed and Fuel Efficiency? Explain.
7. g) Do you think this is the appropriate model for that association? Explain.