• Graphite productionDownload .TXT file Open in Data Desk ?Link
  • Methods: Quality Control
  • Source: invented
  • Number of Cases: 25
  • Story:

    A graphite manufacturer makes long
    rolls of flexible graphite to be used to seal components in
    combustion engines. The specifications state that the mean
    strength should be 21.2 ounces per square yard with a
    standard deviation of 0.29. Further specifications state that
    no roll should have strength less than 20.2 or more than
    22.2 ounces per square yard. If there is a defect in terms
    of the strength of the graphite rolls, the seal will not hold.
    After the roll is created, a beta scanner takes readings of
    the basis weight in ounces per square yard. The data is
    separated into 10 lanes with 20 scans in each lane. A sample
    consists of one roll from each lane. The results from 20
    samples follow are in the data.

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