Which of the following are variables?
(1) and (3) are variables. (2) and (4) are constants.
Read through the explanations below to be sure that you understand why each is correct.

1. Price of a gallon of gas. This is a variable. If you drive a car, you have probably noticed that the price of a gallon of gas changes frequently.
2. Number of inches in a foot. This is a constant. There are always 12 inches in a foot.
3. Number of leaves on a tree. This is a variable. The leaves on a tree will change when new ones grow and others fall off the tree.
4. Capacity of the gas tank of your car. This is a constant. The size of the gas tank in a car does not change. While the number of gallons of gas in a car may vary, the capacity (the maximum amount of gas that it can hold) of the tank does not.

If you got any of these wrong and still do not understand why, read through the definitions at the beginning of the unit. When you are comfortable with the definitions of constant and variable, continue on with this unit.

[review beginning of unit]	[continue on with unit]