Find the domain and range of the following relation:

The domain is $\{1,2,3,4\}$ and the range is $\{120,100,180,240\}.$

The ordered pairs in this example can represent pairs of variables like the set of house numbers and floor areas, bank tellers' numbers and the number of customers they serve on a given day, or the page numbers of a certain book and the number of words on particular pages.

The relation A can also be illustrated using a scatter plot (a two-dimensional graph consisting of points whose coordinates represent the values of the variables under study), as shown in the following figure: