First, we find the volume of the gel which is a rectangular prism in shape: \(V=lwh\)

\(V=(20)(6)(6)\)

\(V=720\) cubic inches

Then, we convert this cubic foot. Since \(1 ft = 12 in\)., then \((1 ft)^3 = (12 in.)^3\) or \(1 ft^3 = 1728 in.^3\) so:

\(V=720\) cubic inches \(\times\)(1 cubic foot/1728 cubic inches)\(=\frac{5}{12}\) cubic foot

We find the weight of the gel by multiplying the density by the volume:

(54 pounds/cubic foot)\(\times\frac{5}{12}\) cubic foot=22.5 pounds