Bourke, CFA, is a fixed income portfolio manager at an insurance company. She has an obligation to pay $175.0 million in 8 years and she wants to immunise this obligation. The yield to maturity of an 8-year zero coupon bond is 6.0% but there are insufficient numbers of these bonds available in the open market. She has, however, identified the following three non-callable semi-annual pay corporate bonds as suitable hedging instruments to immunise the obligation: Price Coupon Yield 83.62 4.0% 7.0% 95.65 113.75 8.0% 5.00% 5.5% 6.0% (a) Which two securities should Bourke use to immunise her obligation? Fully explain your answer (with graphs, where appropriate). State any assumptions. (b) (17 marks) Based on your answer to part (a), above, how many securities must Bourke trade to immunise the obligation. (18 marks)