a company's weighted average cost of capital is 10.9% per year. A project requires an investment of $45,000 today and it is expected to generate after-tax cash flows of 20,000 at the end of year 1, 15,000 at the end of year2, 10,000 at the end of year 3, and 5,000 at the end of year 4. What is the projects payback period?