After strip-mining for coal, the state land office requires the mining company to restore the land to its condition prior to mining. One of many factors that is considered is the pH of the soil, which is an important factor in determining what types of plants will survive in a given location. The area to be mined was divided into grids before the mining took place. Fifteen grids were randomly selected, and the soil pH was measured before mining. When the mining was completed, the land was restored, and another set of pH readings was taken on the same 15 grids; see the accompanying table.

a. What is the level of significance of the test for a change in mean pH after reclamation of the land?
b. What is the research hypothesis that the land office was testing?
c. Estimate the change in mean soil pH after strip-mining using a 99% confidence interval.
d. The land office assessed a fine on the mining company because the t test indicated a significant difference in mean pH after the reclamation of the land. Is the assessment of the fine supported by the data? Justify your answer using the results from parts (a) and (c).

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Location 34 5678 1 12 1 1 15 Before 10.0 10.16 9.96 10,0 987 10.05 10.07 10.08 10.05 10.04 10,09 10.09 9.92 10.05 10.13 After 10.21 10.16 10.1 1010 1007 10.13 10.08 10.30 1017 10.10 10.06 10.37 1024 10.19 10.13