Answer:
3.17 years
Step-by-step explanation:
We can calculate the duration of Investment by duration formula,
Duration= Sum of (PV of each cashflow x year)
PV of each cash flow can be understood as Dolar return % given in the Question.
Year1 Year2 Year3 Year4
Duration= (12% x 1) + (18% x 2) + (11% x 3) + (59% x 4)
Duration= 0.12 + 0.36 + 0.33 + 2.36
Duration= 3.17 years
Note: (100%-12%-18%-11%)59% can be calculated as the remainder of 100% after deducting each year's %.