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Reading proficiency: An educator wants to construct a 99% confidence interval for the proportion of elementary school children in Colorado who are proficient in reading. Part 1 of 3 (a) The results of a recent statewide test suggested that the proportion is 0.61. Using this estimate, what sample size is needed so that the confidence interval will have a margin of error of 0.04? A sample of 987 elementary school children is needed to obtain a 99% confidence interval with a margin of error of 0.04. Part: 1 / 3 Part 2 of 3 (b) Estimate the sample size needed if no estimate of p is available. A sample of elementary school children is needed to obtain a 99% confidence interval with a margin of error of 0.04