Question

Out of 500 people sampled, 395 had kids. Based on this, construct a 95% confidence interval for the true population proportion of people with kids.

Give your answers as decimals, to four places

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Answer 1

Sample proportion (phat) = 180/400 = 0.45z-critical value for 95% confidence interval is z-score for probability = 0.975 = 1.96CI = phat +/- z-critical value * sqrt((phat)(1-phat)/sample size) = 0.45 +/- 1.96 * sqrt(0.45 * 0.55/400) = 0.45 +/- 0.049 = 0.401, 0.499