Anxiety levels are usually elevated in persons with low-esteem, although there are gender differences in the extent to which this is true. In a random sample of 24 17-year olds females with known low self-esteem the average anxiety score on a standard test was 7.62 with a standard deviation of 3.45. Construct a 95% confidence interval for the true mean anxiety score on this scale for 17-year-old females with self-esteem problems. What is the margin of error associated with this confidence interval?
I've already done the 95% confidence interval and got (6.16, 9.08) but I'm a little stuck on the margin of error part. There's a formula Z(standard deviation/square root n).