Question4: Interest on an Investment (20 marks) Some online discount brokerage firms offer flat rates for trading stock, but many still charge commissions based on the transaction amount (principal). Table 1 shows the commission schedule for one of these firms. Table 1: Commission Schedule Principal Commission Under $3,000 $32 +1.8% of Principal $3,000 - $10,000 $56 + 1% of Principal Over $10,000 $106 +0.5% of Principal An investor purchases 75 shares of a stock at $37.90 per share. After 150 days, the investor sells the stock for $41.20 per share. Using the commission schedule shown in tablet: a. Find the annual rate of interest, r, earned by this investment. (10 marks) b. How much interest is earned? (5 marks) c. Explain and interpret how the commission schedule in Table 1 specifies a piecewise-defined function with independent variable P, the principal. Write and specify the function