#### Answer

This relation between "Level of education" and "Average income" represents a function.
Domain:
$\left\{\text{Less than 9th grade, 9th-12th grade, High School Graduate, Some College, College Graduate}\right\}$
Range:
$\left\{\$18,120, \space\$23,251, \space\$36,055, \space\$45,810, \space\$67,165\right\}$

#### Work Step by Step

According to the definition of a function, it has to be a relation where each value from the first set is paired with exactly one element from the second set of elements.
In this example, each of the 5 values from the first set: "Level of education" is paired with exactly one element from the second set: "Average income." Therefore, this relation represents a function.
The function has:
Domain:
$\left\{\text{Less than 9th grade, 9th-12th grade, High School Graduate, Some College, College Graduate}\right\}$
Range:
$\left\{\$18,120, \space\$23,251, \space\$36,055, \space\$45,810, \space\$67,165\right\}$