Answer:
a. 2.50 years
Step-by-step explanation:
The payback period do not take into account of time value of cashflow, thus we ignore the rate of return in this calculation.
The investment for new system in $750,000, then it need cash flow in year 1 of $350,000; year 2 of $325,000 and $75,000 in year to get full back $750,000.
$75,000 is 50% of total cash flow $150,000 in year 3, then it takes 0.5 year 3.
So the payback period of this project is year 1 + year 2 + 0.5 year 3 = 2.5 years.