6-21. Two mutually exclusive design alternatives are being considered for purchase. Doing nothing is also an option. The estimated cash flows for each alternative are given below The MARR is 8% per year. Using the PW method, which alternative, if either, should be recommended? State your assumptions and your reasoning in arriving at a recommendation. (6.5D) Alternative 1 Alternative 2 $18,000 $22,000 Capital investment $9,000 $11,000 Annual revenues $2,900 $4,000 Annual expenses $500 12 years 30.6% $2.000 MV at end of useful life Useful life 4 years 16 5% IRR