For each variable, determine whether it is best thought of as discrete or continuous.


a. The time it takes to drive from home to work (or school)

b. The number of students, in a class of 35, who improve their score from the first midterm to the second midterm.

c. The actual length of a roll of plastic wrap advertised to be 30 feet long.

d. The fuel efficiency, in miles per gallon, of an American-made car