The volume of any prism is just the area of the base times the height of the prism.
The base of the prism is a triangle, and you should know how to find the area of a triangle already. The base is 9, the height is 4, [tex]\frac{bh}2=\frac{9*4}2=\frac{36}2=\boxed{18\ ft^2}[/tex].
Multiply that by the height of 9.5 and we get [tex]18\ ft^2*9.5\ ft=\boxed{\boxed{171\ ft^3}}[/tex]
