6-34. Potable water is in short supply in many countries. To address this need, two mutually exclusive water purification systems are being considered for implementation in China. Doing nothing is not an option. Refer to the data below and state your key assumptions in working this problem. (6.5) System 1 System 2 Capital investment $100,000 $150,000 Annual revenues 50,000 70,000 Annual expenses 22,000 40,000 MV at end of useful life 20,000 0 Useful life 5 years 10 years IRR 16.5% 15.1%

a. Use the PW method to determine which system should be selected when MARR = 8% per year.

b. Which system should be selected when MARR = 15% per year?