A borrower has L=$238,000. She makes loan interest payments at the end of each 6month period for N=8 years with loan interest computed using an annual effective discount rate of d=6.5%. Each time (i.e., every 6 months) she makes the required interest payment, she in addition deposits into a sinking fund earning a nominal annual interest rate of 4.2% convertible monthly. The amount of each sinking fund deposit is D for the first 3 years (i.e., 6 total deposits each of D) and then 2D for each deposit for the remaining 5 years, at which point the amount in the sinking fund equals L. Find D