1) The number of students who belong to the dance company at each of several randomly selected small universities is shown here. Estimate the true population mean size of a university dance company with 95% confidence.
21 25 32 22 28 30 29 30 47 26
35 26 35 26 28 28 32 27 40 45
2) A pizza owner wishes to find the 95% confidence interval of the true mean cost of a large plain pizza. How large should the sample be if she wishes to be accurate to within $0.15? A previous study showed that the standard deviation of the price was $0.26.