The graph of the function f shown in the accompanying figure gives the elevation of that part of the Boston Marathon course that includes the notorious Heartbreak Hill. Determine the intervals (stretches of the course) where the function f is increasing (the runner is laboring), where it is constant (the runner is taking a breather), and where it is decreasing (the runner is coasting).
A) Decreasing on , increasing on , and constant on
B) Decreasing on , increasing on , and constant on
C) Decreasing on , increasing on , and constant on

Question

The graph of the function f shown in the accompanying figure gives the elevation of that part of the Boston Marathon course that includes the notorious Heartbreak Hill. Determine the intervals (stretches of the course) where the function f is increasing (the runner is laboring), where it is constant (the runner is taking a breather), and where it is decreasing (the runner is coasting). 
A) Decreasing on , increasing on , and constant on 
B) Decreasing on , increasing on , and constant on 
C) Decreasing on , increasing on , and constant on

Quizplus · Accepted Answer

The function f is decreasing on the interval from approximately mile 18 to mile 19.5 (marked as "Heartbreak Hill" on the graph), since the elevation is decreasing during this stretch. The function is then increasing on the interval from mile 19.5 to mile 22, since the elevation is increasing. Finally, the function is constant on the interval from mile 22 to mile 24, since the elevation remains relatively flat during this stretch. Option B matches these intervals exactly.

The Graph of the Function F Shown in the Accompanying