The height of the prism is 18 inches
The volume of a rectangular prism is the area of its base multiplied by the height
As we can see here, we have to multiply all the sides to get the volume
Mathematically;
[tex]\begin{gathered} V\text{ = L }\times B\text{ }\times H \\ 11,520\text{ = 20}\times32\times H \\ \\ H\text{ = }\frac{11,520}{20\times32}\text{ = 18 inches} \end{gathered}[/tex]