Use the commission schedule from Company B shown Principal (Value of Stock) Commission in the table to find the annual rate of interest earned on Under $3,000 $32 +1.8% of principal the investment. (Note: commisions are rounded to the $3,000 - $10,000 nearest cent.) $56 +1.% of principal Over $10,000 $106 +0.5% of principal An investor purchases 320 shares at $36.06 a share, holds the stock for 330 days, and then sells the stock for $42.18 a share. Assume a 360-day year. The annual rate of interest is %. (Round to three decimal places.)