Consider the graph to the right: Grade Point Average, GPA,14 is measured on the vertical axis; Leisure on the horizontal axis. For the purpose of this discussion we'll define Leisure as any waking activity not related directly to school, so this student does not have to work (lucky student). Also, for the purposes of this example, we will assume that we have a maximum of 100 hours of leisure and that a 4.0 is the maximum grade point average available at this student's school.

As we noted before, not all students are equal. We are considering the trade-offs faced by one particular student. If this student spends all 100 hours available to her each week in leisure activities, never attends her classes, never studies, does not even show up for tests, she will fail every course and have a 0 GPA. This is the point labeled F on the diagram.

14 We are assuming that the school in question is on a 4 point GPA system, though the same type of trade-offs would hold, and thus the same type of graph, for any GPA system.