Use the sample data to construct a 95% confidence interval estimate of the mean of the lead concentrations for the population of all such medicines.

If a safety standard requires lead concentrations less than 7 mg/g, does it appear that the population mean is less than that level?

3.0 6.5 6.0 5.5 20.5 7.5 12.0 20.5 11.5 17.5