answer all questions please

15. A company is considering buying a computer with the following costs and interest rate. initial cost $3900 salvage value $1800 useful life 10 years annual maintenance $390 interest rate 69 Most nearly, what is the equivalent uniform annual cost (EUAC) of the computer? (A) $740 (B) $780 (C) $820 (D) $850 20. An engineer is evaluating two options for distribut- ing products from a production facility: renting or own ing trucks. The effective annual interest rate is 8%. Most nearly, how many miles must the trucks be driven annually for the two options to have equivalent costs? rent trucks own trucks 80.20/mi purchase cost of $8000 useful life of 5 yr resale value of $2000 after 5 yr annual maintenance cost of $0.09/mi (A) 8800 mi (B) 12,000 mi (C) 15,000 mi (D) 20,000 mi 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%