Answer
$f(x) = -(x+5)^2+13.2$
Work Step by Step
Start by graphing the data and the functions in the same figure window.
$$\begin{aligned}
f(x) &= -(x+5)^2+16.2 \ ,\ k= 16.2\\
f(x) &= -(x+5)^2+15.2 \ ,\ k= 15.2\\
f(x) &= -(x+5)^2+14.2 \ ,\ k= 14.2\\
f(x) &=-(x+5)^2+13.2 \ ,\ k= 13.2\\
\end{aligned}$$ The graph shows that the parabola that best fit the data is $$f(x) = -(x+5)^2+13.2.$$.
