A research group wants to estimate the proportion of consumers who plan to buy a scanner for their PC during the next 3 months.
a. How many people should be sampled so that the sampling error is at most 0.04 with a 90% confidence interval?
b. What is the sample size required if the confidence is increased to 95%, keeping the sampling error the same?
c. What is the required sample size if the research group extends the sampling error to 0.05 and wants a 98% confidence level?