Bond A is a 4-year bond with a 10% coupon rate and Bond B is a 2-year bond with a 20% coupon rate. Both bonds have a face value of £100, and all coupons are paid annually, starting in year 1. Consider...

Bond A is a 4-year bond with a 10% coupon rate and Bond B is a 2-year bond with a 20% coupon rate. Both bonds have a face value of £100, and all coupons are paid annually, starting in year 1. Consider a portfolio that consists of one unit of Bond A and one unit of Bond B. The yield curve is flat at ? = 5%. What is the Macaulay duration of this portfolio?