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.