Problem: City mileage, highway mileage. We expect a car's highway gas mileage to be related to its city gas mileage. Data for all 1040 vehicles in the government's 2010 Fuel Economy Guide give the regression line Highway mpg = 6.554 + (1.016 * city mpg) for predicting highway mileage from city mileage.
Requirement:
1. What is the slope of this line? Say in words what the numerical value of the slope tells you.
2. What is the intercept? Explain why the value of the intercept is not statistically meaningful.
3. Find the predicted highway mileage for a car that gets 16 miles per gallon in the city. Do the same for a car with city mileage 28 mpg.
4. Draw a graph of the regression line for city mileages between 10 and 50 mpg. (Be sure to show the scales for the x and y axes.)