Given data
Length = 18 inches
Width = 1 foot
Height = 1/3 foot
First, make sure all dimensions have the same unit.
Foot to inches conversion
1 foot = 12 inches
Therefore,
18 inches = 18/12 feet = 3/2 foot
[tex]\begin{gathered} Length\text{ = }\frac{3}{2}\text{ ft} \\ \text{Width = 1 ft} \\ Height\text{ = }\frac{1}{3}\text{ ft} \\ \text{Volume = Length x Width x Height} \\ =\text{ }\frac{3}{2}\text{ }\times\text{ 1 }\times\text{ }\frac{3}{2} \\ =\text{ }\frac{9}{4} \\ =\text{ 2}\frac{1}{4}ft^3 \end{gathered}[/tex]