A researcher wishes to? estimate, with 99% ?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 5?% 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 20?% of the respondents said they think their president can control the price of gasoline.
?c) Compare the results from parts? (a) and? (b).
(a) What is the minimum sample size needed assuming that no prior information is? available?
?(b) What is the minimum sample size needed using a prior study that found that 20?% of the respondents said they think their president can control the price of? gasoline?
(c) Does it reduce raise or stay the same?