The Girl Scouts would like to estimate the proportion of people who consider Thin Mints to be their favorite Girl Scout cookie. A pilot sample of 60 cookie customers found that 15 favored Thin Mint cookies. 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

Quizplus · Accepted Answer

The 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 141. This can be calculated using the formula: n = (Z^2 * p * q) / e^2, where Z is the z-score for the desired confidence level (90% in this case), p is the sample proportion (15/60 in this case), q is 1-p, and e is the margin of error (0.06 in this case).

The Girl Scouts Would Like to Estimate the Proportion of People