X-BAR CONTROL CHART FOR 6-INCH NAILS
Every ?ve minutes, a random sample of 3 six-inch nails is selected from a manufactured lot and measured for conformance to the speci?cation. The data in Table 22.1 is a record of the measurements determined over the ?rst hour of a shift. Obtain an X-bar chart and identify whether or not the manufacturing process is "in-control".