Answer:
With a discounted rate of 10%, the payback period of the project is closest to three years.
Step-by-step explanation:
To calculate this a Net Present Value (NPV) formula is needed. With a discounted rate of 10%, the NPV is calculated for different project's length (from year 6 to year 1, with the initial investment in year zero). The closest to value zero in NPV will correspond to the year where project payback is achieved. In this case, year 3 is the closest NPV to zero