A chemical industry discharges a waste contaminated with trichloroethylene (TCE) to the city sewer system. By law, the concentration of TCE must be 1 mg/L or less. To enforce this law, the Department of Environmental Conservation (DEC) conducts random testing. The chief environmental engineer for the chemical company knows that the mean TCE concentration in the waste is 0.064 mg/L, and the standard deviation is 0.022 mg/L. The TCE concentration can be assumed to be a normal random variable. What is the probability that the company will fail a random test by the DEC? [In other words, the probability that a random sample will have TCE > 0.1 mg/L.] Show your work and draw a labeled sketch to show what area of the normal distribution curve you used to solve the problem. What is the probability that the company will fail two consecutive random tests? The tests can be assumed to be independent of each other. Show your work. Determine the concentration of TCE that is exceeded only 10% of the time. Show your work.

Chemistry & Chemical Reactivity
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ISBN:9781133949640
Author:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel
Publisher:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel
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SectionL.2: Making Measurements: Precision, Accuracy, Experimental Error, And Standard Deviation
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A chemical industry discharges a waste contaminated with trichloroethylene (TCE) to the city sewer system. By law, the concentration of TCE must be 1 mg/L or less. To enforce this law, the Department of Environmental Conservation (DEC) conducts random testing. The chief environmental engineer for the chemical company knows that the mean TCE concentration in the waste is 0.064 mg/L, and the standard deviation is 0.022 mg/L. The TCE concentration can be assumed to be a normal random variable.

    1. What is the probability that the company will fail a random test by the DEC? [In other words, the probability that a random sample will have TCE > 0.1 mg/L.] Show your work and draw a labeled sketch to show what area of the normal distribution curve you used to solve the problem.
    2. What is the probability that the company will fail two consecutive random tests? The tests can be assumed to be independent of each other. Show your work.
    3. Determine the concentration of TCE that is exceeded only 10% of the time. Show your work.
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