Suppose a company has a forklift but is considering purchasing a new electric lift truck that would cost $18000 and has operating cost of $3000 in the first year. For the remaining years, operating costs increase each year by 30% over the previous years operating costs. It loses 30% of its value every year from the previous years salvage value. The lift truck has a maximum life of eight years. The firms required rate of return is 4%. Find economic service life of this new machine. Explain your answer.