Consumer demand for small, economical automobiles depends somewhat on recent trends in the average price of unleaded gasoline. For example, consider the information given in the file S04_26.xlsx on the distributions of average annual sales of the Honda Civic and the Toyota Prius in relation to the trend of the average price of unleaded fuel over the past two years.
a. Find the annual mean sales levels of the Honda Civic and the Toyota Prius.
b. For which of these two models are sales levels more sensitive to recent changes in the average price of unleaded gasoline?
c. Given the available information, how strongly associated are the annual sales volumes of these two popular compact cars? Answer by calculating the correlation between them. Provide a qualitative explanation of the results.