38. Imani earned grades of 95, 87, and 83 on the first 3 exams in the class. Each of these exams is worth 20 percent of the total grade in the class and the Final Exam is worth 40 percent of the class grade (there is no extra credit possible and these are the only graded assignments in the class). What grade must Imani earn on the final exam to achieve a final course average of 93 (which will guarantee that she gets a letter grade of A in the class)? 39. Ed invests $68,000 in certificates of deposit (i.e., CDs) paying 1.75%. How much additional money does he need to invest in stocks that are expected to generate a return of 11.8% so that the average return on all of Ed's investments is 7.5%? 40. A rich merchant had collected many gold coins. He did not want anybody to know about them. One day, his wife asked, "How many gold coins do you have?" After pausing a moment, he replied, "Well! If I divide the coins into two unequal numbers, then 25 times the difference between the two numbers equals the difference between the squares of the two numbers." How many gold coins does the rich merchant have