The trench has the shape of a rectangular prism.
The volume of a rectangular prism is
V = length * width * height, or simply
V = LWH
We now use the given dimensions in the formula to find the volume,
V = 150 ft * 2.5 ft * 2 ft = 750 ft^3
The volume of the tranch is 750 ft^3.
The assistant is paid $0.95 per cubic foot, so we now multiply this unit rate by the total number of cubic feet in the trench.
pay = unit rate * volume
pay = $0.95/(ft^3) * 750 ft^3 = $712.50
Answer: The assistant is paid $712.50.
