BHP Billiton has some debt outstanding and must make payments to customers of $7 million in 1 year and $2 million in 4 years. The yield curve is flat at 5%. Required: a) If BHP wants to fully fund its obligation to this customer with a zero-coupon bond, what maturity bond must it purchase? What alternative does BHP have other than one zero- coupon bond? Explain in detail and show all workings. (4 marks) b) What must be the total face value and total market value of the zero-coupon bond in part a)? How does this relate to your alternative in part a)? (3 marks) c) What is convexity and its relation to duration? (3 marks)