A teacher informs her invertebrate physiology class (of 500 students) that a test was very difficult, but the grades would be curved. Scores on the test were normally distributed with a mean of 41 and a standard deviation of 9.7. The maximum possible score on the test was 100 points. Because of partial credit, scores were recorded with 1 decimal point accuracy. (Thus, a student could earn a 41.7, but not a 40.12.) The grades are curved according to the following scheme. Find the numerical limits for each letter grade. Letter Scheme Interval A Top 8% B Scores above the bottom 65% and below the top 8% C Scores above the bottom 35% and below the top 35% D Scores above the bottom 8% and below the top 65% F Bottom 8%