According to a poll conducted by American Express, 35% of people living in the United States use the Internet when planning their vacation.
a. To conduct a follow-up study that would provide 95% confidence that the point estimate is correct to within plus-or-minus 0.04 of the population proportion, how large a sample size is required?
b. To conduct a follow-up study that would provide 99% confidence that the point estimate is correct to within plus-or-minus 0.02 of the population proportion, how large a sample size is required?