Appliances unlimited (au) sells refrigerators. any refrigerator that fails before it is three years old is replaced for free. of all refrigerators, 2% fail during their first year of operation; 4% of all one-year-old refrigerators fail during their second year of operation; and 6% of all two-year-old refrigerators fail during their third year of operation. a. use simulation to estimate the fraction of all refrigerators that will have to be replaced. b. it costs $750 to replace a refrigerator, and au sells 15,000 refrigerators per year. if the warranty period were reduced to two years, how much per year in replacement costs would be saved?