You wish to estimate, with 95% confidence, the population proportion of U.S. adults who say that chocolate is their favorite ice cream flavor. Your estimate must be accurate within 5% of the population proportion.

(a) No preliminary estimate is available. Find the minimum sample size needed.

(b) Find the minimum sample size needed, using a prior study that found that 28% of U.S. adults say that chocolate is their favorite ice cream flavor.

(c) Compare the results from parts (a) and (b).