Answer:
4.04 years / 4 years
Step-by-step explanation:
Payback period is the time period in which initial investment of the asset recovered from it benefit. In this question $280,000 is initially invested in the system. The recovery schedule of $280,000 is follow
Year Net Operating Costs New Benefits Net Cash Flow Balance
0 ($280,000) $0 ($280,000) ($280,000)
1 ($6,000) $40,000 $34,000 ($246,000)
2 ($9,800) $80,000 $70,200 ($175,800)
3 ($11,000) $82,000 $71,000 ($104,800)
4 ($14,000) $115,000 $101,000 ($3,800)
5 ($15,000) $120,000 $105,000 $101,200
6 ($25,000) $140,000 $115,000 $216,200
First fours years have recovered the amount in the fifth year on $3,800 is recovered against initial investment out of $105,000
So,
Payback period = 4 years + $3,800 / $105,000 = 4.04 years