George invests 4000 in a fund. Six months later, he invests 3000 in the same fund. One year from the date of the first investment, the fund has grown to 10000. The fund's rate of return is X per annum compounded semiannually, X > 0. Determine X. O a. 5% O b. 50% c. 2.5% O d. 100% e. 25%