Reading proficiency: An educator wants to construct a 99.9% confidence interval for the proportion of elementary school children in Colorado who are proficient in reading. Part: 0 / 3 Part 1 of 3 (a) The results of a recent statewide test suggested that the proportion is 0.77. 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 elementary school children is needed to obtain a 99.9% confidence interval with a margin of error of 0.05. X 5