It is important to be able to identify the domain and range of a function in order to understand the meaning and the relationship between independent and dependent variables. The following problem relates domain and range to a real world situation.

A baseball fan was sitting in the stands when, in the 7th inning, a Texas Rangers player hit a homerun. As the player began to run the bases, the fan decided to record the time it took the player to touch each of the bases including home plate. The distance between any two bases is 90 feet. What is the domain and range of this situation if the independent variable is the distance in feet the player ran and the dependent variable is the amount of time it took him to run to each base?

In the following sections, you will be able to identify the domain and range for this problem when the function is given in the form of a set of ordered pairs, a table, and a mapping diagram.