The fictional Zantec Tool Company manufactures metal washers used as locking devices. One of the parameters that determine the quality of a washer is its diameter. The company’s manufacturing process used to produce the washers has a mean of 50 millimeters with a standard deviation of 1 millimeter. The company monitors the production process every hour by measuring the average diameter of the washers using a sample size of 25.

1. Construct a mean chart for this process using 3σ control limits.

2. During a 10-hour operation of this process, the washers had the following average diameters (in mms): 50.3, 49.9, 50.2, 49.7, 51.0, 49.5, 49.8, 50.3, 50.6, and 49.8. Is the process in control?