What is the payback period of the following prject initial investment 50000 projected life 8 years net cash flows year1 5000?

In this question only cash inflow for year 1 is provided but if the project life is 8 years then cash inflows and outflows of 8 years are required to find out the payback period of this project but if it is assumed that the cash inflow of year 1 of 5000 is continues for all 8 years then project will unable to even recover its cost as 5000 * 8 = 40000 so the project will bear a loss of 10000.