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Homework Help: Analysis necessary to reduce the concentration of PCBs

  1. Jul 5, 2010 #1
    Hello

    i have a problem with my homework and i hope someone can help me? because i really dont know how to calculate this
    so its translated with google translate :blushing:

    Major customer PCB (polychlorinated biphenyls, a hazardous substance used in
    manufacture of transformers and capacitors), bring in small quantities PCBja
    wastewater environment. Permissible concentration in water PCBja standard 5ppm
    (Parts per million). Factory Administration issued internal instructions that must be stopped
    production if the average concentration in the effluent PCBja exceed 3 ppm. Analysis
    effluent in 50 random samples taken showed an average of 3.20 ppm PCBs, with
    0,23 scattering ppm (squared).
    Calculate:
    A: are the results of the analysis is conclusive proof that it is necessary to stop production
    B: is based on the analysis necessary to reduce the concentration of PCBs in the effluent
    C: if you were the head of the factory, what would be your action on the basis of the analysis carried out
     
  2. jcsd
  3. Jul 6, 2010 #2
    Re: Statistics

    Please show us what work you have done on this problem, so that we can better help you. In particular, what do you think would constitute as conclusive proof?
     
  4. Jul 6, 2010 #3
    Re: Statistics

    n=50
    x=3ppm
    xi=3.2ppm
    s2=0.23ppm2
    s=0.48ppm
    λ=(3.2ppm-3ppm)/0.48ppm=0.42

    hmmm...
     
  5. Jul 6, 2010 #4
    Re: Statistics

    or is it like this
    t=(3.2ppm-3ppm)/0.48ppm * √n =2.97
    H(S=95%,n-1) x=μ--> t=2.0092
    2.97<2.0092 (not true)
    H(S=99%, n-1) x≠μ t=2.6802
    2.97>2.6802 (true)
     
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