The U.S. Department of Energy provides fuel economy information for a variety of motor vehicles. A sample of 10 automobiles is shown in Table 1.6 (Fuel Economy website, February 22, 2008). Data show the size of the automobile (compact, midsize, or large), the number of cylinders in the engine, the city driving miles per gallon, the highway driving miles per gallon, and the recommended fuel (diesel, premium, or regular).

a. How many elements are in this data set?

b. How many variables are in this data set?

c. Which variables are categorical and which variables are quantitative?

d. What type of measurement scale is used for each of the variables?