Kira, a nurse manager at a local hospital, wanted to know more about the hospital's full-time nurses. She polled 12 nurses at random who work full-time at the hospital. The findings in the poll were that these nurses take, on average, 5.5 sick days per year, that $50 \%$ of them would prefer a four-day work schedule, and that 8 of them are married. Kira didn't know that the top hospital administrators had already surveyed all nurses who work full-time at the hospital. In that survey, it was found that the nurses take, on average, 5.7 sick days per year, that $61 \%$ of them would prefer a four-day work schedule, and that 77 of them are married.
(a) For Kira's poll, identify the population and the sample.
Population: (Choose one)
Sample: (Choose one)
(b) Choose whether each number described below is a parameter or a statistic for Kira's poll.
\begin{tabular}{|l|c|c|}
\hline Number & Parameter & Statistic \\
\hline The 77 nurses who are married among all the full-time nurses at the hospital & 0 \\
\hline The $61 \%$ of all the full-time nurses at the hospital who prefer a four-day work schedule & 0 & 0 \\
\hline The average of 5.5 sick days per year taken among the randomly chosen nurses & 0 & 0 \\
\hline
\end{tabular}

Step 1 ：The population in a statistical study is the entire group that you want to draw conclusions about. The sample is the specific group that you will collect data from. In this case, the population would be all the full-time nurses at the hospital, since Kira wants to draw conclusions about this group. The sample would be the 12 nurses that Kira polled, since this is the group she collected data from.

Step 2 ：A parameter is a number that describes a population, while a statistic is a number that describes a sample. The 77 nurses who are married among all the full-time nurses at the hospital would be a parameter, since it describes a characteristic of the entire population of full-time nurses.

Step 3 ：The 61% of all the full-time nurses at the hospital who prefer a four-day work schedule would also be a parameter, since it describes a characteristic of the entire population of full-time nurses.

Step 4 ：The average of 5.5 sick days per year taken among the randomly chosen nurses would be a statistic, since it describes a characteristic of the sample of 12 nurses that Kira polled.

Step 5 ：Final Answer: Population: All full-time nurses at the hospital Sample: The 12 nurses that Kira polled \begin{tabular}{|l|c|c|} \hline Number & Parameter & Statistic \\ \hline The 77 nurses who are married among all the full-time nurses at the hospital & 1 & 0 \\ \hline The $61 \%$ of all the full-time nurses at the hospital who prefer a four-day work schedule & 1 & 0 \\ \hline The average of 5.5 sick days per year taken among the randomly chosen nurses & 0 & 1 \\ \hline \end{tabular}