The Girl Scouts would like to estimate the proportion of people who consider Thin Mints to be their favorite Girl Scout cookie. The total sample size needed to construct a 90% confidence interval for the proportion of customers who favor Thin Mint cookies with a margin of error equal to 6% is .

Question

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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 90% confidence interval, Z is approximately 1.645. Assuming p = 0.5 for maximum variability, and E = 0.06, the calculation gives n ≈ 188.

The Girl Scouts Would Like to Estimate the Proportion of People