Question

You are at a wetland site. You have been instructed to test for chromium contamination. Suppose that a regulatory agency has determined that a population mean chromium concentration equal to 7 mg/kg characterizes the no-contamination state. Likewise, a population mean chromium concentration significantly greater than 7 mg/kg characterizes the contamination state. Suppose that 12 soil tests were conducted around different areas around the wetland site. Their chromium concentration analyzed with the following results. Use this information for the first 9 problems. Do not round show all steps for problem.

6.223 6.995 10.333 7.265 7.833 7.111

6.986 8.934 9.167 7.505 7.301 7.213

1. Describe the population of interest and hypothesized parameter for this scenario.

2. Find the mean of the sample. Use the formula and show the steps for finding the sample mean.

3. Find the median of the sample. Use the formula and show the steps for finding the sample median.

4. Find the standard deviation of the sample. Use the formula and show the steps (add steps to another page if necessary).

5. Using the appropriate symbols, write the hypotheses.

6. Calculate the test statistic showing the work with the formula.

7. Using StatCrunch, determine the p-value for the hypothesis test using the appropriate probability distribution (do not just use the t test for a single mean output).

8. Make the decision for the test in terms of the null hypothesis. Explain how you arrive at this decision.

9. Write the conclusion with minimal statistical jargon and answer the research question of interest as demonstrated in the presentations.

Answer 1