This question doesn't even make sense to me. Please help.

Compute limits for the sample mean x around =12 such that, as long as a new sample mean is within those limits, the process will be considered to be operating satisfactorily. If x exceeds the upper limit or if x is below the lower limit, corrective action will be taken. For quality control purposes, these limits are referred to as lower and upper control limits, respectively: Lower Control Limit = (Round answers to 4 decimal places) Upper Control Limit = (Round answers to 4 decimal places)