An eldarly man starts a retirement account by depositing Tk.10 lakhs now and Tk. 20,000 each month for 20 years. How much money can be with-drawn per month for 15 years if he makes his first withdrawal 12 months after his last deposit? Assume that the interest rate 10% per year compounded semiannually and 10.5% per year. In this case, which interest rate he should select and why