Ged Bryant

Want to test magic number 30. Take any group of people, good party trick. Bet any one present that two or more of the group will have the same birthday. Month and date. This has 98% confidence.

I suggest the Joe Juran “Quality Control Handbook” McGraw Hill Publisher. It will walk you through this and a thousand other questions..

If you are targeting zero defects, you will need a 4% sample, if there are 20 or more discernable characteristics. Establish a lot system, shift, tool change, operator change etc. Reject on one defect per lot.
30 characteristics will not yield Zero.
10 or less characteristics can use 2%.
If you have an AQL you will never yield zero.