First of all, you ask for the 20 listed test scores, but you list 21. For the purpose of this answer, I'll drop the last score (73). Next, I will assume that the highest score possible is 100. So divide each test score by 100 to determine its percentile rank. EXAMPLE TEST SCORE PERCENTILE RANK 86 = 86% 75 = 75% If you want to determine the class rank, and since the highest grade obtainable is 100, just number the test scores from most to least. EXAMPLE

__TEST SCORE____CLASS RANK____% CLASS RANK____MEANING__98 = 1st TOP 6.37% This student did 93.63% better than the rest 92 = 2nd TOP 12.3% This student did 87.7% better than the rest The class average is 1539 / 20 = 76.95 10 Students did better than the average score 10 Students did worse than the average score I hope this makes sense and that I have answered your question!