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(20 points) You have a debt of $60,000 on which you are paying 10% annual effective interest but not principal. You plan to pay it off in 3 years. To prepare for that you invest now 15,000 in a bond with modified duration 1.80, and 45,000 in a bond with modified duration Dmod, in order to Redington immunize your position against small changes in the yield rate. The annual effective yield rate for each of the bonds is 10%. Calculate Dmod