Which of the following random variables are discrete, and which are continuous?
a. The number of passengers on a flight from Toronto to Paris
b. The time it takes you to drive to work in the morning
c. The number of cars that arrive at the local car dealership for an express oil-change service on Wednesday
d. The time it takes to cut a customer's lawn
e. The number of soft drinks a student buys during one week
f. The kilometres driven on one tank of gas