On November 1, 2001, EPA adopted new standards for arsenic in drinking water equal to a maximum 10 ppb. Every few months, an environmental engineer working with the Western UP Health Department collects samples from a local drinking water utility to see if the data demonstrate that the mean concentration of Arsenic exceeds the 10 ppb standard. Assume that sample values are normally distributed about the true mean. Suppose that the most recent set of 7 sample values yielded a sample average of 14.36 ppb and a sample standard deviation of 4.76 ppb. A. Specify the appropriate null and alternative hypotheses to demonstrate that the mean concentration of arsenic exceeds the standard or 10 ppb.
B. What is the rejection region for a 1% test?
C. What do you conclude for this data set?