In a public opinion poll 48% of 189 respondents favor an elimination of taxes on dividend income. How many respondents would be needed to calculate a 95% confidence interval (for the proportion of people who favor an elimination of taxes on dividend income) that has a total width no greater than 4% (the estimate must be within +or - 2% of the true population proportion)?
Solution. This is about the least sample size problem. As we know that the margin of error ME<=2%, and the sample mean of the proportion of people ...
The solution determines the number of respondents required.