Answer:
63 cubic inches.
Step-by-step explanation:
The volume of a prism is given by, A = [tex]\frac{1}{3} \times (\textrm {Base Area}) \times (\textrm {Height})[/tex]
The base area for a square prism with sides s inches is s² sq. inches.
So, the volume of a square prism with a height of 21 inches and each side of the base s inches is given by the expression, V = 7s² cubic inches.
Therefore, if s = 3 inches, then volume will be, V = 7(3²) = 63 cubic inches. (Answer)