Final answer:
Voluntary sampling is when participants choose to be included in a sample. An example of this is when a woman in the airport hands out questionnaires to travelers sitting near gates and not taking naps while they wait to evaluate the airport's service.
Step-by-step explanation:
An example of voluntary sampling is when a woman in the airport hands out questionnaires to travelers sitting near gates and not taking naps while they wait to evaluate the airport's service. This is voluntary because the travelers who choose to participate are self-selecting into the sample. By not asking travelers who are busy or not interested, the sample could be biased, but it is still considered voluntary sampling.
In contrast, the other scenarios provided depict different sampling methods:
- Scenario a demonstrates 'convenience sampling', as the woman in the airport selects participants who are easily accessible and fit her criteria of not being in a hurry or sleeping.
- Scenario b shows 'systematic sampling', as the teacher selects specific rows and then chooses all students from those rows.
Therefore, voluntary sampling is exemplified in scenario c with self-selected samples, reflecting a non-random and potentially biased approach to data collection.