You wish to estimate, with 90% confidence, the population proportion of U.S. adults who are confident in the stability of the U.S. banking system. Your estimate must be accurate within 3% 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 43% of U.S. adults are confident in the stability of the U.S. banking system.

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