Solved: A study was conducted by the Department of Zoology

Chapter 10, Problem 10.41

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A study was conducted by the Department of Zoology at Virginia Tech to determine if there is a signicant dierence in the density of organisms at two dierent stations located on Cedar Run, a secondary stream in the Roanoke River drainage basin. Sewage from a sewage treatment plant and overow from the Federal Mogul Corporation settling pond enter the stream near its headwaters. The following data give the density measurements, in number of organisms per square meter, at the two collecting stations: Number of Organisms per Square Meter Station 1 Station 2 5030 4980 2800 2810 13,700 11,910 4670 1330 10,730 8130 6890 3320 11,400 26,850 7720 1230 860 17,660 7030 2130 2200 22,800 7330 2190 4250 1130 15,040 1690 Can we conclude, at the 0.05 level of signicance, that the average densities at the two stations are equal? Assume that the observations come from normal populations with dierent variances.