Asimple index of three stocks have opening values on day 1 and day 8 as shown in the table below. day 1 shares. price per share. 4000. $3.15 5000. $4.30 6000. $4.60 day 8 shares. price per share 4000. $3.50 5000. $3.90 6000. $4.50 stock abc - 4000 stock xyz - 5000 stock qrs - 6000 what is the rate of change of this simple index over one week? round your answer to the nearest tenth. a. 2.0% b. -1.2% c. 1.2% d. -2.0%