How's the economy? A pollster wants to construct a 95% confidence interval for the proportion of adults who believe that economic conditions are getting better.
Part 1 of 2
(a) A poll taken in July 2010 estimates this proportion to be 0.23. Using this estimate, what sample size is needed so that
the confidence interval will have a margin of error of 0.05?
A sample of adults is needed to obtain a 95% confidence interval with a margin of
error of 0.05.
Part: 1 / 2
Part 2 of 2
(b) Estimate the sample size needed if no estimate of p is available.
A sample of adults is needed to obtain a 95% confidence interval with a margin of error
of 0.05.