A researcher wants to construct a 99% confidence interval for the proportion of elementary school students in Seward County who receive free or reduced-price school
Lunches. What sample size is needed so that the confidence interval will have a margin of
Error of 0.07?
A) 24
B) 277
C) 339
D) 10

Question

Quizplus · Accepted Answer

To calculate the sample size for a proportion with a given margin of error, we use the formula: n = (Z^2 * p * (1-p)) / E^2. For a 99% confidence interval, Z is approximately 2.576. Assuming p = 0.5 for maximum variability, and E = 0.07, the calculation gives a sample size of approximately 339.

A Researcher Wants to Construct a 99% Confidence Interval for the Proportion