Problem: Which of the following patterns on an averages chart that displayed 25 sample averages would reveal an out of control process?
1. sample averages scattered in a seemingly random pattern within the 3-sigma control limits
2. half the sample average above the center line and the other half below the center line
3. the first third of the sample average above the center line, the next third below the center line, and the final third above the center line
4. allof the above (A,B, C) suggest an out of control process