To find the volume of the composite figure, we need to find the volume of the cube and the prism separately, and then add them together.
Volume of the cube = side^3 = 5^3 = 125 ft^3
Volume of the prism = length x width x height = 1.5 x 5 x 2 = 15 ft^3
Total volume = 125 ft^3 (cube) + 15 ft^3 (prism) = 140 ft^3
The correct answer is:
140 ft^3