It is conjectured that when fields are overgrazed by cattle there will be a substantial reduction in the available grass during the subsequent grazing season due to the compaction of the soil. A horticulturist at the state agricultural experiment station designs a study to evaluate the conjecture. Twenty-one plots of land of nearly the same soil texture and suitable for grazing are selected for the study. Three grazing regimens selected for evaluation are randomly assigned to 7 plots each. After the 21 plots are subjected to the grazing regimens for four months, the researcher randomly selects 10 soil cores from each plot and measures the bulk density (g/cm3) in each soil core. The mean soil density of the 10 cores from each plot is given in the following table.

a. Do the grazing regimens appear to yield different degrees of effect on the amount of compacting in the soil? Justify your answer using an μ = .05 test.
b. Provide the level of significance of your test.
c. Do any of the conditions necessary for conducting your test appear to be violated? Justify your answer. 

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Grazing Regimen Continuous grazing Three-week grazing, one-week no grazing 120 148 354 103 14 140 2.68 Iwo-week grazing, two-week no grazing 123 66 170 129 126 05 2.35 Soil Density (g/cn 2.05 3.05 312 59 383 153 144