A lake is 928 acres and has a depth of 17 feet, how may cubic feet of water is in the lake? Any shape that has the same shape and area of cross-section all the way through is a prism. The equation for calculating the volume of a prism is the cross- sectional area of the prism multiplied by its length. If we assume the depth everywhere is 17 feet, then the lake is a prism. The area of the lake's cross-section, i.e., its surface is 928 acres Since 1 Acre = 43560 ft², 928 Acres = 928×43560 ft² = 40423680 ft² Volume = (Area of cross-section)×(height, which in this case is depth) Volume = 40423680 ft² × 17 ft = 687202560 ft³ Edwin AnlytcPhil@aol.com