Answer:
The best height will be of 3.5 as it provides the best expected present worth.
Explanation:
2.0 heights Cost $100,000 now and it is expected to have losses of 300,000 every three years:
Present Value of Annuity
C 300,000
time 16.67
(50 years of useful life / 3 years expected flood)
rate 0.404928
(we capitalize the 12% annual into a 3-year rate)
PV $738,308.8983
Present Worth: 100,000 + 738,308.90 = 838,308.90
2.5 height: cost $165,000, and we expected damage every eight year:
Present Value of Annuity
C 300,000
time 6.25 (50 years useful life / 8 years)
rate 1.475963176 (we capitalize the 12% annual into a 8-year rate)
PV 203,257.0478
Present worth: 203,257.05 + 165,000 = 368,257.05
3.0 cost $300,000, and we expect a flood every 25 years
PV $18,685.0464
Present worth: 300,000 + $18,685.0464 = 318,685.05
3.5 cost $400,000, and we expect a floor every 50 years:
PRESENT VALUE OF LUMP SUM
Maturity 300,000.00
time 50.00
rate 0.12
PV 1,038.05
Cost: 400,000 + 1,038.05 = 401,038.05