Advantage Milling Devices is preparing to buy a new machine for precision milling of special metal alloys. This device can earn $275 per hour, and can run 3,100 hours per year. The machine is expected to be this productive for four years. If the interest rate is 6%, what is the present value? What is the present value if the interest rate is not 6%, but 0%? Why does present value fall when interest rates rise?