6.2 Margin of error and the confidence interval. A study of stress on the campus of your university using the College Undergraduate Stress Scale (CUSS) reported an average stress level of 1123 (a higher score indicating more stress) with a margin of error of 43 for 95% confidence. The study was based on a random sample of 400 undergraduates. a. Give the 95% confidence interval. b. If you wanted 99% confidence for the same study, would your margin of error be greater than, equal to, or less than 43