A researcher wishes to? estimate, with 90?% ?confidence, thepopulation proportion of adults who are confident with their?country's banking system. His estimate must be accurate within 5?%of the population proportion. ?(a) No preliminary estimate isavailable. Find the minimum sample size needed. ?(b) Find theminimum sample size? needed, using a prior study that found that25?% 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 thatno prior information is? available?
