Portfolio X consists of a one-year zero-coupon bond with a face value of $3,000 and a 10-year zero-coupon bond with a face value of $7,000. Portfolio Y consists of a 6.25-year zero-coupon bond with a face value of $5,500. Assume that the current yield on all these bonds is 8% per annum.

(i) Calculate the duration for both the portfolios.

(ii) Calculate the percentage changes in the values of the two portfolios for a 0.1% per annum increase in yields.

(iii) Calculate the percentage changes in the values of the two portfolios for a 5% per annum increase in yields.