The overall length of a cigar lighter body used in an automobile application is controlled using control charts.

The overall length of a cigar lighter body used in an automobile application is controlled using control charts. The following table gives length for 20 samples of size 4 (measurements are coded from 5.00 mm; that is, 15 is 5.15 mm).

1. Using Excel set up the appropriate control chart using these data.
2. Estimate the process mean and standard deviation
3. Does the overall length of the cigar lighter seem to be normally distributed?
4. Specifications are 5.10 ± 0.05 mm. What can you say about the process capability?
5. What fraction of cigar lighters is likely to be greater than the upper specification limit?