Discussion:
Q: An election poll reported that a candidate had an approval rating of 48% with a margin of error E of 3%. Construct a confidence interval for the proportion of adults who approve of the candidate.
You are a travel agent and wish to estimate, with 95% confidence, the proportion of vacationers who plan to travel outside the United States in the next 12 months. Your estimate must be accurate within 3% 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 26% of the respondents said they planned to travel outside the United States in the next 12 months.
(c) compare the results from parts (a) and (b)