Assuming that the yield curve is flat at 7%, what is the duration of a liability portfolio that has $4 Million due in 3 years and $10 Million due in 7 years? Hint: The setup of this calculation is similar to spreadsheet 11.1 in the bondPortfolios.pptx slide deck. The duration is the weighted average of the payment times, where a weight is determined by the present value of the payment (relative to the total of the present values). The payment times in spreadsheet 11.1 are 1, 2, and 3 (corresponding to the three-year maturity of the bond in that example); the payment times here will be 3 and 7.