Antigen titer. A vaccine manufacturer analyzes a batch of products to check its titer. Immunologic analyses are imperfect, and repeated measurements on the same batch are expected to yield slightly different titers. Assume titer measurements vary according to a Normal distribution with mean and = 0.070. (The standard deviation is a characteristic of the assay.) Three measurements demonstrate titers of 7.40, 7.36, and 7.45. Calculate a 95% confidence interval for the true concentration of the sample