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.

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Part 1 of 3

(a) The results of a recent statewide test suggested that the proportion is

0.65

. 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 elementary school children is needed to obtain a 99.9% confidence interval with a margin of error of 0.04 .