Assume you have a portfolio of zero-coupon bonds. The first bond is 10 year bond and the other bond is 5 year bond with. Assume the CURRENT Market value of the first bond is 150,000,000 while the second bond is short and has a market value of -300,000,000. There is also a cash position of 250,000,000 Both bonds are Zero coupon bonds. What is the duration of this portfolio? Hint: Use the weighted average formula

a)-0.5

b)+0.5

c)None of the Above

d)0.0