4. A pension fund has the following liability: A 20-yr annuity, that will pay coupons of 7% at the end of each year.(t=1...t=20). The pension fund's liability has a face value of 100. The yield curve is flat at 5%. The same pension fund has the following assets: one share of a 1-yr zero-coupon bond with face value 100, and one share of a 20-yr zero-coupon bond which also has a face value of 100. Calculate the PV and duration of the portfolio of assets. 4. A pension fund has the following liability: A 20-yr annuity, that will pay coupons of 7% at the end of each year.(t=1...t=20). The pension fund's liability has a face value of 100. The yield curve is flat at 5%. The same pension fund has the following assets: one share of a 1-yr zero-coupon bond with face value 100, and one share of a 20-yr zero-coupon bond which also has a face value of 100. Calculate the PV and duration of the portfolio of assets