The quality control group of a manufacturing company is planning to use control charts to monitor the production of a certain part. The specifications for the part require that each unit weigh between 13.0 and 15.5 ounces with a target value of 14.25. A sample of 75 observations results in the following:

a. Are the specifications consistent with the statistical variation in the sample?
(Hint: Use the computing formula for the sample variance:

b. What problems do you anticipate if the group attempts to use X and R charts for this process?

c. If the 75 observations are statistically stable, what percentage of the manufactured items will fall outside the tolerances?

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75 = 1,065, i=1 75 = 15,165. i=1