The nearest whole number, the volume of the composite figure is 1140 in^3.
The composite figure consists of two rectangular prisms. The first prism has dimensions 8 in. x 4 in. x 18 in., and the second prism has dimensions 10 in. x 4 in. x 18 in.
To find the volume of the composite figure, we need to subtract the volume of the hollow cylinder from the volume of the two rectangular prisms.
The volume of a rectangular prism is calculated as follows:
Volume = length x width x height
The volume of the first rectangular prism is therefore:
Volume = 8 in. x 4 in. x 18 in. = 576 in^3
The volume of the second rectangular prism is therefore:
Volume = 10 in. x 4 in. x 18 in. = 720 in^3
The volume of a cylinder is calculated as follows:
Volume = π * radius^2 * height
Since the cylinder in the middle of the prism is hollow, we only need to consider the volume of the cylinder wall. The radius of the cylinder is 1 in., and the height of the cylinder is 18 in. Therefore, the volume of the cylinder wall is:
Volume = π * 1 in.^2 * 18 in. = 56.52 in^3
The total volume of the composite figure is therefore:
Volume = (576 in^3 + 720 in^3) - 56.52 in^3 = 1140.48 in^3
To the nearest whole number, the volume of the composite figure is 1140 in^3.