Solved: High concentration of the toxic element arsenic is all toocommon in groundwater

Chapter 7, Problem 52

(choose chapter or problem)

High concentration of the toxic element arsenic is all toocommon in groundwater. The article Evaluation ofTreatment Systems for the Removal of Arsenic fromGroundwater (Practice Periodical of Hazardous, Toxic,and Radioactive Waste Mgmt., 2005: 152157) reportedthat for a sample of water specimens selected fortreatment by coagulation, the sample mean arsenic concentrationwas 24.3 mg/L, and the sample standard deviationwas 4.1. The authors of the cited article used t-basedmethods to analyze their data, so hopefully had reason tobelieve that the distribution of arsenic concentration wasnormal.a. Calculate and interpret a 95% CI for true average arsenicconcentration in all such water specimens.b. Calculate a 90% upper confidence bound for thestandard deviation of the arsenic concentration distribution.c. Predict the arsenic concentration for a single water specimenin a way that conveys information about precisionand reliability.