In accordance with the case of Dave’s Burgers, it states that service times should be no more than 2.0 minutes and should average less than 1.5 minutes. The service times from the table above shows that there are twenty-one observations that are greater than 2.0 minutes. This means these observations do not fall in this range. Also, there are fifteen average means and ranges that are greater than 1.5 minutes. That means they do not fall in this range as well. According to the control charts above, both X-bar chart and R-chart definitely have a few different results. On X-bar chart, there are two sample means fall outside the preset control limits. In other words, this X-bar chart is not in control. On the other hand, all plots of data in
