Volume of Water in an Aquarium

A rectangular aquarium has dimensions of 3 feet in length, 2 feet in width, and 1.5 feet in height.

The owner wants to fill the aquarium with water, but he will first add a decorative layer of gravel that will take up 0.5 feet in height. What will be the volume of water that he can actually fill within the aquarium after adding the gravel?

The formula for the volume of a rectangular prism is given by: $$ V = l imes w imes h $$ where $$ l $$ is the length, $$ w $$ is the width, and $$ h $$ is the height.