The painful wrist condition called carpal tunnel syndrome can be treated with surgery or, less invasively, with wrist splints. Recently, a magazine reported on a study of 154 patients. Among the half that had surgery, 83% showed improvement after three months, but only 47% of those who used the wrist splints improved. a) What is the standard error of the difference in the two proportions? b) Create a 90% confidence interval for this difference. c) State an appropriate conclusion.