The Wilson Company uses a great deal of water in the process of making industrial milling equipment. To comply with federal clean-water laws, it has a water purification system that all wastewater goes through before being discharged into a settling pond on the company’s property. To determine whether the company is complying with federal requirements, sample measures are taken every so often. One requirement is that the median pH level must be less than 7.4. A sample of 95 pH measures has been taken. The data for these measures are shown in the file Wilson Water.
a. Carefully examine the data. Use an appropriate procedure to determine if the data could have been sampled from a normal distribution.
b. Based on the sample data of pH level, what should the company conclude about its current status on meeting federal requirements? Test the hypothesis at the 0.05 level.