A portfolio includes three discount bonds: one paying Shs.3,000,000,5 years from now, one paying Shs.2,500,000, 10 years from now, and one paying Shs.2,000,000, 15 years from now.

i) What is the duration of the portfolio when the term structure of forward rates is flat at 6%?

ii) What is the duration of the portfolio when the term structure of forward rates is flat at 7%?