Is exposure to a chemical in Teflon-coated cookware hazardous? Perfluorooctanoic acid (PFO...

Is exposure to a chemical in Teflon-coated cookware hazardous? Perfluorooctanoic acid (PFOA) is a chemical used in Teflon-coated cookware to prevent food from sticking. The Environmental Protection Agency is investigating the potential risk of PFOA as a cancer-causing agent (Science News Online, August 27, 2005). It is known that the blood concentration of PFOA in the general population has a mean of μ = 6 parts per billion (ppb) and a standard deviation of σ = 10 ppb. Science News Online reported on tests for PFOA exposure conducted on a sample of 326 people who live near DuPont’s Teflon-making Washington (West Virginia) Works facility.

a. What is the probability that the average blood concentration of PFOA in the sample is greater than 7.5 ppb?

---

b. The actual study resulted in  = 300 ppb. Use this information to make an inference about the true mean (μ) PFOA concentration for the population that lives near DuPont’s Teflon facility.