Question 16

Given the following process control data for a normally distributed quality variable (four samples of size five each):

SAMPLE			MEASUREMENTS
8 AM	11.6	11.9	12.2	12.0	11.8
9 AM	12.1	11.8	11.9	12.0	11.8
10 AM	11.8	12.9	12.1	12.8	11.9
11 AM	12.0	12.2	12.1	12.2	13.0

If the process is known to have a mean of 12.0 and an average range of 0.5 (5 observations per sample), using three-sigma control limits, do any of the sample means indicate an out-of-control process, and if so, which specifically? (calculate all control limits to 2 decimal places)

Group of answer choices

No, all sample means within control limits so process in control

Yes, measurements 11.6, 12.9, 12.8, 13.0 out of control, so process may be out of control

Yes, all sample means out of control limits, so process may be out of control

Yes, 1000AM and 1100AM sample means outside limits, so process may be out of control