## Elementary Statistics (12th Edition)

a) $x=3005\cdot 0.817=2455.085\approx2455.$ b)The best point estimate is equal to the proportion of the sample (x) divided by the sample size: $\hat{p}=\frac{x}{n}=0.817.$ $E=z_{\frac{\alpha}{2}}\cdot \sqrt{\frac{\hat{p}\cdot (1-\hat{p})}{n}}=1.645\cdot \sqrt{\frac{0.817cdot (1-0.817)}{3005}}=0.012.$ Confidence interval: $\hat{p}-E$