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 RangeDetected Allowable Maximum

Chromium 0.40 to 0.56 100

Barium 0.006 to 0.0162 2

Fluoride 1.09 to 1.184 4

For each substance, estimate thestandard deviationby assuming uniform distribution and normal distribution (Round your answers to 4 decimal places.)

Uniform Distribution Normal Distribution

Chromium ? ?

Barium ? ?

Fluoride ? ?