Molded-rubber expansion joints, used in heating and air-conditioning systems, are designed to have internal diameters of 5 inches. To monitor the manufacturing process, one joint was randomly selected each hour from the production line and its diameter (in inches) measured, for a period of 12 hours, as shown in the table. The data will be used to construct a variable control chart.

a. Locate the center line for the variable control chart.

b. Locate upper and lower control limits.

c. Does the process appear to be in control?

Transcribed Image Text:

RUBBERJNT Hour Diameter Hour Diameter 1 5.08 7 5.02 2 4.88 8 4.91 4.99 9 5.06 4 5.04 10 4.92 5 5.00 11 5.01 6. 4.83 12 4.92 3.