Suppose one of the products manufactured by Pittsburgh Plate and Glass (PPG) is a glass pane that is 3/ 8 in., thick. One of the quality control measurements is the variability in the thickness of the glass panes. If the standard deviation for the thickness of the glass exceeds 0.01 in., the process is considered out of control and needs to be corrected. The glass thickness, in inches, as measured from a random sample of 25 panes can be found in the Excel file PPG.xlsx.
a. Using α = 0.05, determine if the process variability is out of control.
b. Verify your results using PHStat.
c. Interpret the p value obtained from the software.

  • CreatedJuly 28, 2015
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