It is known that after the concrete is adjusted by trial mixing, the amount of various materials is: cement 3.10kg, water 1.86kg, sand 6.24kg, crushed stone 12.8kg, and the apparent density of the mixture is 2500kg ∕ m3 . : (1)How much is the amount of per cube concrete material? (2)If the moisture content of sand at the construction site is 2.5%, and the moisture content of stone is 0.5%, find the construction mix ratio.

An external consultant recommends that a plant installs a bank of capacitors for power factor correction. this will reduce the peak electrical demand charges by an average of 93 kw every month. the plant current pays $13 per kw in peak demand charges. the capacitor bank will include 223 kw of fixed capacitors, and 183 of variable capacitors. the fixed capacitors cost $59 per kw, and the variable capacitors will cost $65 per kw. the consultant charges 21% of the equipment costs to install the capacitors. because this project will reduce the demand for the electric utility, they are prepared to provide a one-time rebate of $42 per kw of reduced demand. what is the simple payback period for this project (in years)?