The urinary fluoride concentration (parts per million) was measured both for a sample of livestock grazing in an area previously exposed to fluoride pollution and for a similar sample grazing in an unpolluted region:

Does the data indicate strongly that the true average fluoride concentration for livestock grazing in the polluted region is larger than for the unpolluted region? Use the Wilcoxon rank-sum test at level α = .01.

Transcribed Image Text:

Polluted21.3 18.7 23.0 17.1 16.8 20.9 19.7 Unpolluted 14.2 18.3 17.2 18.4 20.0