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computing the capability indices

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  • October 25, 2001 at 12:22 pm #28059

    muhannad al nabulsi
    ★ 20 Years ★
    Participant

    I have tried several times,but I”m confusing,I’m asking for guidance of an expert to solve the following excercise:
    A process was studied and the control limits set at 50.10+/-0.12.The sample size was 5(n=5).If the specifications are 50.00+/-0.20,compute the capability indices (Cp,Cpk,Cpl and Cpu.)Whatpercentage is the process capable?Not capable??show evidence…..Thanks in advance,Appreciate prompt response,regards

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    October 25, 2001 at 1:03 pm #69489

    gt
    ★ 20 Years ★
    Participant

    first:you need to know the mean(u) and  std deviation
    short term indices, where std dev=R/d2
    2nd: Cpk=min((u-lsl)/3stddev, (Usl-u)/3 stddev)
    3rd Cp=(Usl-Lsl)/6 stddev
    for long term we use the Pp and Ppk
    instead of using std dev=R/d2, take the std dev of the sample
    rgds
     
     

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    October 25, 2001 at 1:24 pm #69492

    muhannad al nabulsi
    ★ 20 Years ★
    Participant

    thank you very much for advice,best regards

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    October 26, 2001 at 10:42 am #69524

    kmb
    ★ 20 Years ★
    Participant

    I assume that you’re taking samples of size 5 from a stable process and trying to estimate the capability of your process.  You should check the assumptions, of course.  For more info you may wish to refer to the papers on capability analysis using MINITAB via http://www.minitab.com/company/virtualpressroom/Articles/index.htm including the confidence interval discussion paper.  Hope it helps.
    -KMB

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    October 28, 2001 at 10:20 am #69554

    muhannad al nabulsi
    ★ 20 Years ★
    Participant

    The overall mean of  a set of sampllea is 24.The lower limit on the control chart is  10 and the upper limit is 42.The standard deviation  of the  sample data is 12.0 What is the process capability?
    explain how you calculate it??
    a.over 95%
    b.between 90% and 95%
    c.between 85% and 90%
    d.between 80% and 85
    e.under 80%

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    October 28, 2001 at 12:20 pm #69557

    muhannad al nabulsi
    ★ 20 Years ★
    Participant

    1.WHAT ARE THE ADVANTAGES OF STUDYING  A SAMPLE INSTEAD OF A POPULATION??
    2*sKETCH A BOXPLOT OF THE FOLLOWING STATISTICS:
    SMAALEST=60,MEDIAN=100,LARGEST=115,1st quartile=80,3rd quartile=110
    there are no outliers .comment on the shape of this distribution
    3*Obtain  a newspaper with  a classified section and create a stem-and -leaf plot of the asking prices of 20 automobiles,selected at random

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    October 28, 2001 at 1:36 pm #69559

    muhannad al nabulsi
    ★ 20 Years ★
    Participant

    thank you very much for your kind advice,best regards

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