John's estate is to be divided into three equal parts and invested, to be paid out as follows: (i) John's two children will each receive their share in 20 level annual payments, beginning one year after John's death. (ii) Charity Q will receive its share as equal annual payments in perpetuity beginning 21 years after John's death. Q's annual payment is twice the annual payment for one child. Determine the effective interest rate at which the estate is invested. (CAS 11/93 #9] (A) Less than 5% (B) At least 5% but less than 5.25% (C) At least 5.25% but less than 5.50% (D) At least 5.50% but less than 5.75% (E) At least 5.75%