b) Assume that you hold a portfolio of 2 bonds. Bond A has a market value (price) of 1000 and bond B of 2000. The modified duration of bond A is 3.5 and of bond B 1.4. i. What is the modified duration of your bond portfolio? (10 marks) ii. What is the estimated price change (using duration) of your bond portfolio, if yields increase by 1%? (5 marks) iii. How we can improve the approximation of the previous question, especially for large changes in the yields? Explain your answer in maximum 150 words. (10 marks)