Answer
$\approx 55.6 ft^3$
Work Step by Step
We know that the volume of a cylinder (radius $r$, height $h$) is given by:
$\displaystyle V=\pi r^2 h$
We have a diameter of 4.5 feet. Thus the radius is:
$\displaystyle radius=\frac{diameter}{2}=4.5/2=2.25~feet$
We plug in our values ($h=3.5~ft$, $r=2.25~ft$) to find the volume:
$V=\pi 2.25^2 3.5\approx 55.6 ft^3$
