3. Compute limits for the sample mean around 12 such that, as long as a...

3. Compute limits for the sample mean around µ  12 such that, as long as a new sample mean is within those limits, the process will be considered to be operating satisfactorily. If exceeds the upper limit or if is below the lower limit, corrective action will be taken. These limits are referred to as upper and lower control limits for quality control purposes.