A quality control manager wants the term the percentage of defective lightbulbs in the production line which of the following sampling methods would most likely lead to a valid inference?
Testing the last 4000 bulbs in the production line
Testing The first 2000 lightbulbs in the production line
Testing every 50th lightbulb in the production line
Re-testing 100 lightbulbs that already been tested
Testing every 50th lightbulb in the production line.
This sampling method ensures that a representative sample of lightbulbs from throughout the production process is selected, providing a more accurate estimate of the percentage of defective lightbulbs in the production line. Testing the last 4000 bulbs may not be representative of the entire production process, while testing the first 2000 bulbs may not account for any changes or improvements made later in the production process. Re-testing 100 lightbulbs that have already been tested would not provide new data on the overall percentage of defective lightbulbs.