Answer
Its length was approximately 220.7 feet.
Work Step by Step
Replace the given period into the formula and solve for the length:
$16.5=2\pi\sqrt{\frac{l}{32}}$
$16.5\cdot \frac{1}{2\pi}=2\pi\sqrt{\frac{l}{32}}\cdot \frac{1}{2\pi}$
$ \frac{8.25}{\pi}=\sqrt{\frac{l}{32}}$
$( \frac{8.25}{\pi})^2=(\sqrt{\frac{l}{32}})^2$
$ \frac{68.0625}{\pi^2}=\frac{l}{32}$
$ \frac{68.0625}{\pi^2}\cdot32=\frac{l}{32}\cdot32$
$l=\frac{2178}{\pi^2}\approx220.7$
