A psychology professor assigns letter grades on a test according to the following scheme. A: Top 8% of scores B: Scores below the top 8% and above the bottom 59% C: Scores below the top 41% and above the bottom 23% D: Scores below the top 77% and above the bottom 7% F: Bottom 7% of scores Scores on the test are normally distributed with a mean of 72.3 and a standard deviation of 9.1. Find the numerical limits for a D grade. Round your answers to the nearest whole number, if necessary.