Question: Transmission Housings. Apple, Hammerand, Nelson, and Seow analyzed data taken from a set of 35 transmission housings. In addition to the side cover hole diameter considered in of this chapter, they also examined upper borehole diameters on the transmission housings. For y the hole diameter in inches, the values below concern x = (y - 3.5000)× 104, diameters stated in ten thousandths of an inch above 3.5000 in. Specification limits for the upper borehole diameter were 3.502 ± .002 in. (Below, 19 represents y = 3.5019, 28 represents y = 3.5028, etc.)
(a) What is the subgroup size?
(b) Give appropriate retrospective lower and upper control limits and center line for monitoring the hole diameters.
(c) What does the chart using on your limits from (b) indicate about the stability of the upper borehole diameter production process? Why?