Cost = $4,000
Revenues = $3,200 per year
Life = 5 years
Payback period calculation:
Year ----- Cash flow -------- Investment
Yr 0 ----- ------------ -4,000
Yr 1 ------ 3,200 ----------- -800
Yr 2 ------ 3,200 -------------- 0
Payback period lies between year 1 and 2.
Therefore,
Payback period = 1+ 800/3200 = 1+0.25 = 1.25 years