A train tunnel is modeled by the quadratic function $\displaystyle {h}{\left({x}\right)}=-{0.22}{x}^{{2}}+{28}$, where $\displaystyle {x}$ is the distance, in feet, from the center of the tracks and $\displaystyle {h}{\left({x}\right)}$ is the height of the tunnel, also in feet. Assume that the high point of the tunnel is directly in line with the center of the train tracks.

Round your answers to the nearest tenth as needed.

a) What is the maximum height of the tunnel? feet.

b) How wide is the base of the tunnel? feet.