Final answer:
To find the number of people worldwide who play volleyball weekly, surveys or data from volleyball organizations would be needed, as global participation rates are not specified. Examples of sports engagement levels within groups, such as swim team practice frequency and after-school sports participation, can provide localized insight but don't directly answer the global volleyball question.
Step-by-step explanation:
When trying to determine how many players worldwide play volleyball at least once a week, it's important to recognize that specific global statistics on this frequency of participation may not be readily available.
To estimate this figure, one would have to rely on surveys or data from international volleyball organizations.
However, considering the vast number of participants in various levels of organized and recreational volleyball, it's likely in the millions.
In the examples provided, a community swim team's practice frequency and the participation rates in after-school sports for high school students are given in percentages and specific numbers, which can provide insights on the popularity of sports activity among certain groups.
For instance, 75 advanced swimmers, 47 intermediate swimmers, and the number of those practicing four times a week in each category (40, 30, and 10, respectively) can give us a snapshot of engagement within that swim team.
Similarly, knowing that approximately 8 percent of students participate in after-school sports all four years of high school, we can apply this percentage to different group sizes to estimate participation numbers.
For example, if 60 seniors are chosen at random from a local high school, we can expect that about 8 percent of those selected (0.08 × 60) have participated in after-school sports throughout their high school careers.