Final answer:
The most appropriate tool for monitoring assembly line production and adjusting machinery after detecting a nonconforming unit is a Statistical quality control chart. This allows for continual monitoring of production process stability and quality, quickly detecting deviations, and maintaining consistent product standards.
Step-by-step explanation:
The most appropriate tool for the process described, where every nth unit on an assembly line is sampled for conformance and machinery is adjusted after detecting a nonconforming part, is a Statistical quality control chart. Options like ISO 9000 audit, Fishbone diagram, and Cost of quality report serve different purposes and are not specifically designed for the continual monitoring of production processes as required in the scenario. Statistical quality control charts are used to monitor process stability and quality over time, alerting to any significant variation that may indicate a problem with the production process.
This process falls under the quality management principles where the aim is to maintain process consistency and detect issues before they become significant problems. Utilizing a control chart, supervisors can determine if the process is in control or if there is a trend towards nonconformance, which would trigger maintenance or calibration of the machinery, thereby ensuring product quality and reducing wastage or rework.