In the six sigma quality control model, how many defects are allowed per million?

In the Six Sigma quality control model, the goal is to achieve a level of quality that allows for a maximum of 3.4 defects per million opportunities. This figure stems from the statistical interpretation of what constitutes "Six Sigma" in a normal distribution, where the process is designed to be six standard deviations away from the mean in both directions, thus allowing very few defects.

Achieving this level of quality signifies that a process is extremely capable and efficient, with the expectation that virtually all products or services meet quality standards with only a minor fraction resulting in defects. The number 3.4 represents an exceptionally high standard of performance and is often cited as a benchmark for organizations aiming to improve their processes and reduce waste.

The other options represent significantly higher numbers of allowable defects, which would not align with the Six Sigma standard and thus reflect a lesser emphasis on quality and efficiency.