Consider an investment with an initial cost (=outflow) of -$20,000 and is expected to last for 5 years. The expected cash inflows in years 1 and 2 are $5,000, in years 3 and 4 are $5,500 and in year 5 is $1,000. The total cash inflow is expected to be $22,000 or an average of $4,400 per year. Compute the payback period in years.