A new machine has just been installed to produce printed circuit boards. One of the critical measurements is the thickness of the resistance layer. The quality control inspector randomly selects five boards each half-hour, measures the thickness, and records the results. The measurements (in millimeters) for the period 8:00 a. m. to 10:30 a. m. follow. Thickness (millimeters)
Time 1 2 3 4 5
8:00 87.1 87.3 87.9 87.0 87.0
8:30 86.9 88.5 87.6 87.5 87.4
9:00 87.5 88.4 86.9 87.6 88.2
9:30 86.0 88.0 87.2 87.6 87.1
10:00 87.1 87.1 87.1 87.1 87.1
10:30 88.0 86.2 87.4 87.3 87.8

Mean of the sample means
= LCL = UCL =

Mean of the sample ranges
=LCL = UCL =