Sam looks at his college transcript and says to Kelly, "How is this possible! My grade point average for this semester's courses is higher than my grade point average for last semester's courses, but my cumulative grade point average still went down from last semester to this semester". Explain to Sam how this is possible. Expand this discussion by explaining the relationship between two key variables in 'production and cost in firm chapter' as analogous to that of semester GPA and Cumulative GPA.