The table shows values of a force function $f(x)$, where $x$ is measured in meters and $f(x)$ in newtons. $$\begin{array}{|c|c|c|c|c|c|c|c|c|c|}\hline x & 4 & 6 & 8 & 10 & 12 & 14 & 16 & 18 & 20 \\ \hline f(x) & 5 & 5.8 & 7.0 & 8.8 & 9.6 & 8.2 & 6.7 & 5.2 & 4.1 \\ \hline \end{array}$$ Use the Midpoint Rule to estimate the work done by the force in moving an object from $x = 4$ to $x = 20$.

Midpoint Rule estimate: joules