The control chart for 10 consecutive large samples for Machine B is shown below. What should Luka do, if anything, with Machine B, based on this chart?

1. **Recall Control Chart Rules**: Pay attention to rules about points near the limits. A key rule is that if two consecutive points fall between a warning limit and an action limit, the process should be investigated. 2. **Examine the Chart for Machine B**: * Are any points outside the action lines? No. * Look at the last two points, for sample 9 and sample 10. * Sample 9 has a mean of approx. 25.7g. This is between the upper warning line (25.5g) and the upper action line (26.0g). * Sample 10 has a mean of approx. 25.8g. This is also between the upper warning and action lines. 3. **Apply the Rule**: We have two consecutive points in the warning zone. This is a signal that the process is likely out of control. 4. **Formulate a Conclusion**: Action is required. Luka should stop the machine and investigate the cause of the increased mean mass.