10. (10 points) (a) You are given the following binomial tree of per annum semi-annual com- pounding 0.5-year risk-free interest rates: 7% 50% 5% 50% 4% The risk-neutral probabilities of the "up" and "down" states at t=0.5 are 50%. What is the 1-year interest rate implied by the tree? Please give a per annum semi-annual compounding interest rate.