## Elementary Statistics (12th Edition)

The best point estimate is equal to the proportion of the sample (x) divided by the sample size: $\hat{p}=\frac{x}{n}=\frac{3}{8}=0.375.$ $E=z_{\frac{\alpha}{2}}\cdot \sqrt{\frac{\hat{p}\cdot (1-\hat{p})}{n}}=1.96\cdot \sqrt{\frac{0.375\cdot (1-0.375)}{8}}=0.3355.$ Hence, the confidence interval: E is between $\hat{p}-E$ and $\hat{p}+E$, hence p is between 0.375-0.3355=0.0395 and 0.375+0.3355=0.7105. The results are not that close.