Using t-statistic when population standard deviation is unknown From your sample of n = 17, you know the mean, a? = 46, and the sample standard deviation, 3 = 5. Give an interval estimate of the population mean at a 95% confidence level. (a) Use your confidence level to establish the probability to have a false positive, as. (b) find the number of degrees of freedom, lc, for this problem. (c) Use quantile function ("=tiv()" in Excel) to find the t-statistic that produces the CDF of a/2 and the t-statistic that produces the CDF of 1 - a/2. Illustrate what you found with a sketch of the bell curve. (d) Use the definition of t-statistic, Xi t(xilk) = s/ Vn Together with your t-stats from (c) to find the boundaries of your estimate of the population mean