The proportion of potential graduate students amongst undergraduates in Eurelia is estimated to be somewhere between 20 and 40 percent. How large of a sample would be needed to establish a 90% confidence interval for the proportion if the margin of error is to be only 1.8 percentage points? b) A random sample of 1250 Eurelian undergraduates included 325 potential graduate students. What is a 99% confidence interval for the overall proportion?
Added by Steven H.
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8 percentage points, we can use the formula: n = (z^2 * p * (1-p)) / E^2 where: - n is the sample size - z is the z-score corresponding to the desired confidence level (90% = 1.645) - p is the estimated proportion of potential graduate students (we'll use the Show more…
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