Which of the following are continuous functions of time?

The quantity of gas in the tank of a car on a journey between New York and Boston (continuous or discontinuous)

The number of students enrolled in a class during a semester (continuous or discontinuous)

I want to verify my answers:

Discontinuous for the car

Continuous for the students,

Continuous functions of time are a function if small changes are made to the source then the result will have those small changes in them. The quantity of gas is a continuous function of time because small variations can be made to the quantity of the gas in use to the extent of molecules and atoms whereas same cannot be done to the student as we cannot half them.