Two Cal Poly freshmen gathered data on the prices for a random sample of 30 textbooks from the campus bookstore. They found the average price was $65.02, and the standard deviation of prices was $51.42. Th e data are not strongly skewed.
a. Identify the observational unit for this study.
b. Identify the variable of interest and whether it is categorical or quantitative.
c. Explain how you know from the sample average and sample standard deviation that the distribution of textbook prices is not bell-shaped.
d. In the context of this study, explain why it is valid to use the theory-based (t-distribution) approach to find a confidence interval?

e. Use the Theory-Based Inference applet to find and report a 95% confidence interval for the parameter of interest. Also, interpret the interval in the context of the study.