Easy# Mean Value Theorem: Average Rate of Change

APCALC-OAH1BJ

The function $f$ is continuous over the interval $[6,8]$ and differentiable over $(6,8)$.

If the average rate of change of $f$ over $[6,8]$ is $-\frac { 1 }{ 2 } $, which of the following statements must be true?