Do heavier cars use more gasoline? To answer this question, a researcher randomly selected 15 cars. He collected their weight (in hundreds of pounds) and the mileage (MPG) for each car. From a scatterplot made with the data, a linear model seemed appropriate. The following output was obtained from SPSS: Which of the following descriptions of the value of the slope is the correct description?
a. We estimate the mileage to decrease by 0.521 miles per gallon when the weight of a car increases by 1 pound.
b. We estimate the mileage to decrease by 52.1 miles per gallon when the weight of a car increases by 100 pounds.
c. We estimate the mileage to decrease by 0.521 miles per gallon when the weight of a car increases by 100 pounds.
d. We cannot interpret the slope because we cannot have a negative weight of a car.