Question: one measure of water quality is the concentration of dissolved...
One measure of water quality is the concentration of dissolved oxygen in the water. Previously this has been 4.6 mg/L for a particular location that is downstream from an industrial plant. The manager at the industial plant would like to determine whether recently introduced processes have seen a change in the quality of water in the stream. The following values are the oxygen concentration of water samples collected from that location on 12 randomly selected days:
4.45, 4.35, 4.65, 4.95, 4.15, 4.85, 4.75, 4.85, 4.05, 4.15, 4.02, 4.25.
Determine if the oxygen concentration has changed from 4.6mg/L, at the 5% level of significance. You must state the null and alternative hypotheses, the test statistic, the rejection criterion and the decision and a conclusion in terms of the original problem.