A pollster wants to construct an 80% confidence interval for the proportion of adults who believe that economic conditions are getting better. Estimate the sample size needed if no estimate of

p is available, what sample size is needed so that the confidence interval will have a margin of error of 0.02?

given , Margin of error, E = 0.02 No prior estimate of population proportion is avaliable. so, we assume it as , P = 0 -5 we know that, Margin of 691909, E = Zxxx Pa-P ) 2 80% confidence level of significance, = 0.20 7 Ex = 10282 2 [ from for *= 0.20] Critical 7-value calculator => 0102 = 1282 x 0 .5 x0 . 5 n n = 1028