With a height of 60 in, george was the shortest president of a particular club in the past century. the club presidents of the past century have a mean height of 64.6 in and a standard deviation of 2.9 in. a. what is the positive difference between george's height and the mean? b. how many standard deviations is that [the difference found in part (a)]? c. convert george's height to a z score. d. if we consider "usual" heights to be those that convert to z scores between minus2 and 2, is george's height usual or unusual? a. the positive difference between george's height and the mean is nothing in.