A plasma arc furnace has an internal combustion temperature of ?7,000 degrees°C and is being considered for the incineration of medical wastes at a local hospital. The initial investment is ?$448,000 and annual revenues are expected to be ?$184,000 over the eighteight?-year life of the furnace. Annual expenses will be ?$96,000 at the end of year one and will increase by ?$4,500 each year thereafter. The resale value of the furnace after eighteight years is ?$18,000. a. What is the simple payback period of the? furnace? b. What is the internal rate of return on the? furnace?