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# Use the following to answer the questions below:An environmental studies student working on an ...

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Use the following to answer the questions below:

An environmental studies student working on an independent research project was investigating metal contamination in the St. Lawrence River. The metals can accumulate in organisms that live in the river (known as bioaccumulation). He collected samples of Quagga mussels at three sites in the St. Lawrence River and measured the concentration of copper (in micrograms per gram, μg/g or mcg/g) in the mussels. His data are summarized in the provided table and plot. He wants to know if there are any significant differences in mean copper concentration among the three sites.

 Site Copper Concentration (μg/ g) n                       s 123 19.9       23.4       17.5       25.4       20.5   13.0       18.8       18.4       16.1   18.4       13.8         7.0       11.4       15.2 5        21.34     3.092    4        16.60     2.687    5        13.16     4.274 Overall ​ 14       17.06     4.82

Computer output from the analysis provides the following information about the pairwise differences:

Site = 1 subtracted from:

 Site Lower Center Upper ----+---------+---------+---------+----- 2 -11.040 -4.740 1.560 (---------*----------) 3 -14.120 -8.180 -2.240 (---------*---------) ​ ​ ​ ​ ----+---------+---------+---------+----- ​ ​ ​ ​ -12.0      -6.0          0.0           6.0
Site = 2 subtracted from:

 Site Lower Center Upper ----+---------+---------+---------+----- 3 -9.740 -3.440 2.860 (---------*----------) ​ ​ ​ ​ ----+---------+---------+---------+----- ​ ​ ​ ​ -12.0      -6.0         0.0          6.0
Based on this output, which sites have significantly different means?

▸ Only Sites 1 and 2 have significantly different means.

▸ Only Sites 2 and 3 have significantly different means.

▸ Only Sites 1 and 3 have significantly different means.

▸ None of the sites have significantly different means.
Textbook

## Statistics: Unlocking the Power of Data

Edition: 3rd
Authors:
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chanelstar27chanelstar27
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