The Environmental Protection Agency (EPA) requires that cities monitor over 80 contaminants in their drinking water....

The Environmental Protection Agency (EPA) requires that cities monitor over 80 contaminants in their drinking water. Samples from the Lake Huron Water Treatment Plant gave the results shown here. All observations were below the allowable maximum, as shown by the reported range of contaminant levels. (presumably the mean would be the midrange).

Substance Range Detected Allowable MAX Origin of Substance

Chromium 0.44 to 0.57 100 Discharge from steel and pulp mills, natural erosion

Barium 0.007 to 0.020 2 Discharge from drilling wastes, metal refineries, natural erosion

Fluoride 1.05 to 1.11 4 Natural erosion, water additive, discharge from fertilizer and aluminum factories

For each substance, estimate the standard deviation σ by assuming uniform distribution and normal distribution shown in Table 8.11 in Section 8.8. (Round your answers to 4 decimal places.)

Uniform Distribution Normal Distribution

Chromium

Barium

Fluoride

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orchestra answered 1 year ago

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