4.50 Use of Twitter. Suppose that the population proportion of Internet users who say that they use Twitter or another service to post updates about themselves or to see updates about others is 19%.¹² Think about selecting random samples from a population in which 19% are Twitter users.

1. (a) Describe the sample space for selecting a single person.

2. (b) If you select three people, describe the sample space.

3. (c) Using the results of part (b), define the sample space for the random variable that expresses the number of Twitter users in the sample of size 3.

4. (d) What information is contained in the sample space for part (b) that is not contained in the sample space for part (c)? Do you think this information is important? Explain your answer.