A 95% confidence interval for the population proportion of professional tennis players who earn more than $2 million a year is found to be between 0.82 and 0.88. What was the approximate sample size used to obtain this information?
A) 545
B) 387
C) 382
D) 233

Question

Quizplus · Accepted Answer

The sample size can be approximated using the formula: n = (Z^2 * p * q) / e^2, where Z is the z-score for the desired confidence level, p is the estimated proportion, q is 1 - p, and e is the margin of error. Plugging in the given values, we get: n = (1.96^2 * 0.85 * 0.15) / 0.03^2 = 544.64. The closest answer choice is A) 545.

A 95% Confidence Interval for the Population Proportion of Professional