How many cubic feet of earth must be removed in digging an artificial lake 15 ft. deep, if the level bottom is a rectangle 180 ft. by 20 ft. and the top is a rectangle 202 ft. by 25 ft.?
Area of the top =202 x 25 = 5050 ft^2
Area of the bottom=180 x 20 = 3600 ft^2
Average area of the bottom and the top:
(5050 + 3,600) / 2 = 4,325 ft^2
Volume of earth removed:
15 x 4,325 =64,875 ft^3 - volume of earth to be removed.
This is the volume of a Frustrum:
Volume of frustum of a rectangular pyramid = h/3 * (l*w + sqrt(l*w*l1*w1) + l1*w1)
Length l: 202
Breadth w: 25
Length l1: 180
Breadth w1: 20
Height h: 15
The calculated volume is: 64,569.0056 cu feet.
