Testing and Estimating & with a Known Let a be a random variable that represents micrograms of lead per liter of water (ag/L). An industrial plant discharges water into a creek. The Environmental Protection Agency has studied the discharged water and found a to have a normal distribution, with a = 0.7/g/L (Reference: EPA Wetlands Case Studies). (a) The industrial plant says that the population mean value of c is /4 - 2.0 pag/L. However, a random sample of n - 10 water samples showed that # - 2.56 ug/L. Does this indicate that the lead-concentration population mean is higher than the industrial plant claims? Use 1%