A manufacturer of windows produces one type that has a plastic coating.The specification limits for the plastic coating are 30 and 70.From time to time the plastic coating can become uneven.Therefore,to keep the coating as even as possible,thickness measurements are periodically taken at four different locations on the window.15 subgroups were observed,each consisting of four thickness measurements,with the following results: mean of the means = $\overline { \overline{ x } }$

= 50.05,and average range of 8.85.Find the sigma level capability of the process.
A)4.64
B)-4.66
C)7.83
D)2.25

Question

A manufacturer of windows produces one type that has a plastic coating.The specification limits for the plastic coating are 30 and 70.From time to time the plastic coating can become uneven.Therefore,to keep the coating as even as possible,thickness measurements are periodically taken at four different locations on the window.15 subgroups were observed,each consisting of four thickness measurements,with the following results: mean of the means =

\overline { \overline{ x } }

= 50.05,and average range of 8.85.Find the sigma level capability of the process.

= 50.05,and average range of 8.85.Find the sigma level capability of the process.
A)4.64
B)-4.66
C)7.83
D)2.25

Quizplus · Accepted Answer

The sigma level capability of the process is given by:$$\sigma_{level} = \frac{\overline{x} - LSL}{6\overline{R}}$$where:$$\overline{x}$$ is the mean of the meansLSL is the lower specification limit$$\overline{R}$$ is the average rangeSubstituting the given values into the equation, we get:$$\sigma_{level} = \frac{50.05 - 30}{6(8.85)} = 4.64$$Therefore, the sigma level capability of the process is 4.64.

A Manufacturer of Windows Produces One Type That Has a Plastic