A psychology professor assigns letter grades on a test according to the following scheme. A: Top 10% of scores B: Scores below the top 10% and above the bottom 64% C: Scores below the top 36% and above the bottom 17% D: Scores below the top 83% and above the bottom 6% F: Bottom 6% of scores Scores on the test are normally distributed with a mean of 69.2 and a standard deviation of 7.7. Find the numerical limits for a D grade. Round your answers to the nearest whole number, if necessary.