Answer
$$m=51.8\space \text{ft}$$
Work Step by Step
For a circle of radius $r$, the arc length $s$ corresponding to a central angle $\theta$ (in radians) is given by $s=r\theta$.
Therefore,
$$m=(9 \text{ ft})\bigg(\dfrac{11\pi}{6}\bigg) = \dfrac{33\pi}{2}\space \text{ft} = 51.8\space \text{ft}$$
