A university financial aid office polled a random sample of 954 male undergraduate students and 882 female undergraduate students. Each of the students was asked whether or not they were employed during the previous summer. 700 of the male students and 695 of the female students said that they had worked during the previous summer. Give a 99% confidence interval for the difference between the proportions of male and female students who were employed during the summer.
Find the critical value that should be used in constructing the confidence interval.