2. stanford–binet iq test scores are normally distributed with a mean score of 100 and a standard deviation of 15. a. sketch the distribution of stanford–binet iq test scores. b. write the equation that gives the z score corresponding to a stanford–binet iq test score. sketch the distribution of such z scores. c. find the probability that a randomly selected person has an iq test score i. over 145. ii. under 91