An engineer with Calahan Technologies calculated the AW of cost values shown for a presently owned machine using estimates she obtained from the vendor and company records. A challenger has an economic service life of 7 years with an AW of $-86,000 per year. Assume that all future costs remain as estimated and the challenger s technology will definitely replace that of the defender within 5 years. When should the company purchase the challenger? The company should purchase the challenger in year An engineer with Calahan Technologies calculated the AW of cost values shown for a presently owned machine using estimates she obtained from the vendor and company records. A challenger has an economic service life of 7 years with an AW of $-86,000 per year. Assume that all future costs remain as estimated and the challenger s technology will definitely replace that of the defender within 5 years. When should the company purchase the challenger? The company should purchase the challenger in year