SELF TEST $9\mathrm{.}48$ A quality improvement project was conducted with the objective of improving the wait time in a county health department $($CHD$)$ Adult Primary Care Unit $($APCU$).$ The evaluation plan included waiting room time as one key waiting time process measure. Waiting room time was defined as the time elapsed between requesting that the patient be seated in the waiting room and the time he or she was called to be placed in an exam room. Suppose that, initially, a targeted wait time goal of $25$ minutes was set. After implementing an improvement framework and process, the quality improvement team collected data on a sample of $355$ patients. In this sample, the mean wait time was $23\mathrm{.}05$ minutes, with a standard deviation of $16\mathrm{.}83$ minutes. $($Data extracted from M$.$ Michael, S$.$ D$.$ Schaffer, P$.$ L$.$ Egan, B$.$ B$.$ Little, and P$.$ S$.$ Pritchard, "Improving Wait Times and Patient Satisfaction in Primary Care," Journal for Healthcare Quality, $2013,35(2),$ pp$.50-60.)$ what is the crtical value