This model is the solution to the semiconductor problem as discussed in the class. The model exhibits goal seeking behavior, while centering around the 250 ppm defects introduced with equipment wear and tear, etc.
The model matches real world data in terms of general trajectory, but not totally. There has to be modifications in terms of determining the real defect elimination rates, as opposed to ideal ones. That would make the model more accurate. However, for the purposes of understanding dynamics in goal seeking models, this is a good exercise.
If average defect elimination time is lesser, it leads to faster goal seeking. Any delay (>1 year) makes it impossible to seek the goal in realistic timelines.