Solve Q4-60

What is the present equivalent of the repair expenses at time 0? What is the annual equivalent expense during years 1-5? Maintenance expenses for a bridge on a local river are estimated to be $30,000 per year for the first 10 years, followed by two separate $80,000 expenditures in years 15 and 20. The expected life of the bridge is 30 years. If i = 7% per year, what is the equivalent uniform annual expense over the entire 30-year period