. Quality control charts were developed for the toluene concentration exiting a stack at a manufacturing facility. The following statistics were calculated: = 11.2 ppb, = 1.64. The warning limits are set to be +/- 2 and the control limits are set to be +/- 3. (a) Draw the resulting control chart, indicating the warning and control limits. (b) mark the following measurements (in ppb), taken on consecutive days, on the control chart: 11.5, 13.5., 14.2, 11.9, 10.8, 12.6, 12.8, 15.6, 11.8.

On how many occasions to the measurements exceed the control limits?

On how many occasions to the measurements exceed the warning limits?

What conclusions, if any, can be drawn regarding the precision and accuracy of the measurements?