A researcher wishes to estimate, with 90% confidence, the population proportion of adults who support labeling legislation for genetically modified organisms (GMOs).
Her estimate must be accurate within 6% of the true 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 84% of the respondents said they support labeling legislation for GMOs.
(c) Compare the results from parts (a) and (b).