Suppose you manage a plant that purifies its liquid waste and discharges the water into a local river. An EPA inspector has collected water specimens of the discharge of your plant and also water specimens in the river upstream from your plant. Each water specimen is divided into five parts, the bacteria count is read on each, and the median count for each specimen is reported. The bacteria counts for each of six specimens are reported in the following table for the two locations.

a. Why might the bacteria counts shown here tend to be approximately normally distributed?

b. What are the appropriate null and alternative hypotheses to test whether the mean bacteria count for the plant discharge exceeds that for the upstream location? Be sure to define any symbols you use.

c. The data are submitted to SPSS, and part of the output is shown below. Carefully interpret this output.

d. What assumptions are necessary to ensure the validPlant Discharge ............................................................................................ 30.1 36.2 33.4 28.2 29.8 34.9 ity of this test?