The following measurements (in picocuries per liter) were recorded by a set of radon gas detectors installed in a laboratory facility: 382,361.2,333,348.3,385.1,332.2,380 .7 Using these measurements, construct a 95% confidence interval for the mean level of radon gas present in the facility. Assume the population is approximately normal. Step 2 of 4 : Calculate the sample standard deviation for the given sample data. Round your answer to two decimal places.