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.