Determine the margin of error for a 90% confidence interval to estimate the population mean when s = 42 for the sample sizes below. a) n = 15 b) n=34 c) n=54 a) The margin of error for a 90% confidence interval when n = 15 is (Round to two decimal places as needed.) b) The margin of error for a 90% confidence interval when n-34 is. (Round to two decimal places as needed.) c) The margin of error for a 90% confidence interval when n = 54 is (Round to two decimal places as needed.)