a Use the commission schedule from Company B shown in Table 3 to find the annual rate of interest earned by each investment in Problems 73 and 74. Table 3 Company B Principal Under $3,000 $3,000-$10,000 Over $10,000 Commission $32 + 1.8% of principal $56 + 1% of principal $106 + 0.5% of principal 73. An investor purchases 215 shares at $45.75 a share, holds the stock for 300 days, and then sells the stock for $51.90 a share. In Problems 79-82, assume that the annual interest rate on a credit card is 25.74% and interest is calculated by the average daily balance method. 79. The unpaid balance at the start of a 28-day billing cycle was $955.13. A $5,000 purchase was made on the first day of the billing cycle and a $50 payment was credited to the account on day 21. How much interest will be charged at the end of the billing cycle?