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).

SubstanceRangeDetectedAllowable

MaximumOrigin of SubstanceChromium0.48 to 0.67100Discharge from steel and pulp mills, natural erosionBarium0.004 to 0.0172Discharge from drilling wastes, metal refineries, natural erosionFluoride1.06 to 1.174Natural erosion, water additive, discharge from fertilizer and aluminum factories

For each substance, estimate thestandard deviationby assuming uniform distribution and normal distribution shown inTable 8.11in Section 8.8.(Round your answers to 4 decimal places.)

Uniform DistributionNormal DistributionChromiumBariumFluoride