In 2004, a team of researchers published a study of contaminants in farmed salmon. Fish from many sources were analyzed for 14 organic contaminants. The study expressed concerns about the level of contaminants found. One of those was the insecticide mirex, which has been shown to be carcinogenic and is suspected to be toxic to the liver, kidneys, and endocrine system. Summaries for the mirex concentrations (in parts per million) in the farmed salmon are: .

(1) What assumptions and conditions must be checked before finding a confidence interval?

(2) Find a 95% confidence interval for the mean level of mirex concentrations. Show the formula, not just by Minitab.

(3) Interpret this confidence interval.

(4) Explain what 95% confidence means.