The observations in the table are dissolved oxygen contents in water. The higher the dissolved oxygen content, the greater the ability of a river, lake, or stream to support aquatic life. In this experiment, a pollution-control inspector suspected that a river community was releasing semi treated sewage into a river. To check this theory, five randomly selected specimens of river water were selected at a location above the town and another five below. These are the dissolved oxygen readings (in parts per million):

a. Use a one-tailed Wilcoxon rank sum test with α = .05 to confirm or refute the theory.
b. Use a Student's t-test (with α = .05) to analyze the data. Compare the conclusion reached in part a.

Above Town | 4.8 5.2 5.0 4.9 5.1 Below Town 5.0 4.7 4.9 48 4.9