SDN Members don't see this ad. (About Ads) There's been many posts about figuring out the percentile of someone's score given the mean and SD. Hope this could settle the confusion once and for all. Here's a calculator for percentile: http://bayes.bgsu.edu/nsf_web/jscript/normal_cdf/normal_icdf.htm On the left, put in the mean and SD. On the right, under PROBABIILITY, input the percentile in decimle points. Like .90 for 90th%tile, .30 for 30th%tile then click COMPUTE X, it will tell you the score that corresponds to the percentile you input. For exmple, COMLEX mean 500, SD 79, using probabilty .90, then x = 601. So a 601 corresponds to a 90th%tile.