Most water-treatment facilities monitor the quality of their drinking water on an hourly basis. One variable monitored is pH, which measures the degree of alkalinity of acidity in the water. A pH below 7.0 is acidic, one above 7.0 is alkaline, and a pH is 7.0 is neutral. One water-treatment plant has a target pH of 8.5. The mean and standard deviation of 1 hour's test results, based on 17 water samples at this plant, are 8.42 and 0.16, respectively. (a) Set up the null and alternative hypotheses to test whether the mean pH value mu of the water from the plant differs from 8.5. (b) What test statistic should be used based on the available sample information