A researcher wishes to? estimate, with 95?% ?confidence, the population proportion of adults who are confident with their? country's banking system. His estimate must be accurate within 4% 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 25?% of the respondents said they are confident with their? country's banking system.
?(c) Compare the results from parts ?(a) and ?(b).
?(a) What is the minimum sample size needed assuming that no prior information is? available?
n=
?(Round up to the nearest whole number as? needed.)