hemoglobin determinations were made on sixteen animals exposed to ionizing radiation. the following observations were recorded: 15.6, 14.4, 14.8, 13.8, 16.6, 14.0, 17.4, 17.3, 18.6, 16.2, 15.7, 14.7, 16.4, 13.9, 14.8, 17.5. construct a 95 percent confidence interval for population standard deviation?