In the article "Occurrence and Distribution of Ammonium in Iowa Groundwater" (K. Schilling, Water Environment Research, 2002:177-186), ammonium concentrations (in mg/L) were measured at a large number of wells in the state of Iowa. These included five types of bedrock wells. The number of wells of each type, along with the mean and standard deviation of the concentrations in those wells, is presented in the following table.

Can you conclude that the mean concentration differs among the five types of wells?

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Well Type Sample Size Mean Standard Deviation 53 57 Mississippian Devonian Silurian Cambrian-Ordovician 0.75 0.90 0.68 0.50 0.82 0.90 0.92 1.03 0.97 0.89 67 51