8-8 Your cat's summer kitty-cottage needs a new roof. You feel a 15-year analysis period is in line with your cat's remaining lives. (There is no salvage value for old roofs.) First cost Annual upkeep Thatch Slate $250 $425 65 Service life, in years 3 30 5 (a) Graph the EUAC or EUAW for the alternatives. Construct a choice table for interest rates from 0% to 100%. (b) Which roof should you choose if your MARR is 12%? What is the actual value of the IRR on the incremental cost?