A researcher wishes to estimate, with 95%confidence, the population proportion of adults who think the president of their country can control the price of gasoline. Her estimate must be accurate within 55%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 18%of the respondents said they think their president can control the price of gasoline.