Essex Corp. of St. Louis is a small manufacturer of parts for Boeing’s Aircraft and Missile Systems. In the late 1990s, Essex was trying to establish a SPC program. Part number 528003-N was typical. The following samples of two were observed for a critical dimension of the part (in inches). Tire lower specification, nominal, and upper specification values were .4160, .4185, .4210 inches, respectively.
a. is the process capable?
b. Construct sample mean and sample range control charts. Is the process in control?