This plot allows you to see the average total number of inspected units at various incoming quality levels.

For the camera data, when the average incoming quality level is very good, the sample size is close to what the sampling plan specifies.

When the incoming quality level is low enough to cause lots to be rejected, rework and re-inspection must take place to replace the defectives. Therefore, the average number of lenses that are inspected increases as the lot percent defects increases.

For the camera data, the 3 curves representing the 3 sampling plans are located slightly further to the right than the original plan with a sample size of 259 lenses. As the sample size decreases (curve moves to the right), the average total inspection increases.