to improve package tracking at a ups transfer facility conveyor equipment was upgraded with RFID sensors at a cost of 60000. the future market values are expected to decrease by 20% per year. the operating cost is expected to be 5000 in year 1 with increase of 3000 per year therafter. at an interest rate of 10% per year determine the ecnomic service life of the sensor if the maximum life is 6 years