Answer
It appears that a graph of this function would be concave up, because the average rate of change becomes less negative as $t$ increases.
Work Step by Step
To determine concavity, we calculate the rate of change:
$$
\begin{gathered}
\frac{\Delta f(t)}{\Delta t}=\frac{10-20}{1-0}=-10 . \\
\frac{\Delta f(t)}{\Delta t}=\frac{6-10}{2-1}=-4 . \\
\frac{\Delta f(t)}{\Delta t}=\frac{3-6}{3-2}=-3 . \\
\frac{\Delta f(t)}{\Delta t}=\frac{1-3}{4-3}=-2 .
\end{gathered}
$$
It appears that a graph of this function would be concave up, because the average rate of change becomes less negative as $t$ increases.
