11. A computer with an initial cost of $1500 and an annual maintenance cost of $500/yt is purchased and kept indefinitely without any change in its annual main- tenance costs. The interest rate is 4%. Most nearly, what is the present worth of all expenditures? (A) $12,000 (B) $13.000 (0) $14.000 (D) $15,000 12. A computer with a useful life of 12 vears has an ini- tial cost of $3200 and a salvage value of $100. The inter- est rate is 10%. Using the Modified Accelerated Cost Recovery System (MACRS) method of depreciation and a 10-year recovery period, what is most nearly the book value of the computer after the second year? A S1900 B S2100 $ $2300 D $2100 8. Permanent mineral rights on a parcel of land are pur- chased for an initial lump-sum payment of $100.000. Profits from mining activities are $12,000 each year, and these profits are expected to continue indefinitely. Most nearly, what is the interest rate earned on the initial investment? (A) 8.3% (B) 9.0% (C) 10% (D) 12%