The National Retail Federation conducted a national survey of 8,526 consumers on September 1–9, 2009. Among the findings reported were that:
• 29.6% of those surveyed said that the state of the U.S. economy would affect their Halloween spending plans;
• the average amount that the respondents said they expect to spend on Halloween is $56.31.
a. Are these numbers parameters or statistics? Explain.

b. Determine and interpret a 95% confidence interval based on the 29.6% value given in the article.
c. What additional information would you need to determine a 95% confidence interval based on the $56.31 value given in the article?