An X bar chart includes the following data: The mean of data ranges from 600 to 1,400 on the Y axis. The sample ranges from 0 to 20 on the x axis. The upper control limit is approximately 1,300. The average is approximately 1,000. The lower control limit is approximately 700. The mean stays within the control lines except for one sharp drop below the lower control limit. This drop occurs at approximately 8 on the X axis. After this drop, the mean rises in a positive direction and stays within the control lines through the end of the graph.