Final answer:
Susan's 200 selected students represent a sample, not the population, and the mean number of siblings calculated from this sample is a statistic used to estimate the parameter, which is the mean number for all students at the high school.
Step-by-step explanation:
The correct answer to the question is: d) The 200 selected students is the sample, and the mean number of siblings for all the students is the statistic.
When conducting a study or a survey in statistics, it is important to understand the difference between a population and a sample, as well as the difference between a parameter and a statistic.
The population refers to the entire group that you want to draw conclusions about, whereas the sample refers to a subset of the population that is actually observed or collected data from.
A parameter is a characteristic or measure obtained by using all the data from the entire population. In contrast, a statistic is a characteristic or measure obtained by using only the data from the sample.
In Susan's case, she wants to estimate the mean number of siblings for students in her high school; therefore, the high school students are the population.
The 200 randomly selected students are the sample that Susan will use to calculate the mean number of siblings, which will be used as the statistic to estimate the parameter—the actual mean number of siblings for the entire population of the school.