14.31 Redo Problem 14.8 with the following additional information. - Recall that the current book value of the old machine is $7,810. The new machine will be depreciated under a seven-year MACRS class. - The company's marginal tax rate is 35%, and the firm uses a 10% after-tax MARR. 14.8 A firm is considering replacing a machine that has been used to make a certain kind of packaging material. The new, improved machine will cost $31,000 installed and will have an estimated economic life of 10 years with a salvage value of $2,500. Operating costs are expected to be $1,000 per year throughout the service life of the machine. The old machine (still in use) had an original cost of $25,000 four years ago, and at the time it was purchased, its service life (physical life) was estimated to be seven years with a salvage value of $5,000. The old machine has a current market value of $7,700. If the firm retains the old machine, its updated market values and operating costs for the next four years will be as given in Table P14.8. The firm's MARR is 12%. (a) Working with the updated estimates of market values and operating costs over the next four years, determine the remaining useful life of the old machine. (b) Determine whether it is economical to make the replacement now. (c) If the firm's decision is to replace the old machine, when should it do so