12. Dissolved Oxygen Content Dissolved oxygen content is a measure of the ability of a river, lake, or stream to support aquatic life, with high levels being better. A pollution-control inspector who suspected that a river community was releasing semitreated sewage into a river, randomly selected five specimens of river water 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 a 5.05 to confirm or refute the theory.

b. Use a Student’s t-test (with a 5.05) to analyze the data. Compare the conclusion reached in part a.

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