Answer
The rates of change are decreasing, so we expect the graph of $f(x)$ to be concave down.
Work Step by Step
To determine concavity, we calculate the rate of change:
$$
\begin{gathered}
\frac{\Delta f(x)}{\Delta x}=\frac{1.3-1.0}{1-0}=0.3 \\
\frac{\Delta f(x)}{\Delta x}=\frac{1.7-1.3}{3-1}=0.2 \\
\frac{\Delta f(x)}{\Delta x}=\frac{2.2-1.7}{6-3} \approx 0.167 .
\end{gathered}
$$
The rates of change are decreasing, so we expect the graph of $f(x)$ to be concave down.
