A statistics professor has just given a final examination in his statistical inference course. He is particularly interested in learning how his class of 40 students performed on this exam. The scores are shown below.

What is the mean score on this exam? Place your answer, rounded to two decimal places in the blank. For example, 65.78 would be a legitimate entry.

81 77 73 79 85 86 73 74 77 73 83 81 75 91 95 77 84 76 76 78 78 90 85 84 92 81 90 75 64 82 86 78 86 82 76 70 78 72 93