A student's course grade is based on one midterm that counts as 1010% of his final grade, one class project that counts as 1515% of his final grade, a set of homework assignments that counts as 4040% of his final grade, and a final exam that counts as 3535% of his final grade. His midterm score is 6767, his project score is 8888, his homework score is 9191, and his final exam score is 7272. What is his overall final score? What letter grade did he earn (A, B, C, D, or F)? Assume that a mean of 90 or above is an A, a mean of at least 80 but less than 90 is a B, and so on.