Answer
a)0.61
b)0.0442
c)0.61-0.0442=0.5658
Work Step by Step
a) The best point estimate is equal to the proportion of the sample (x) divided by the sample size: $\hat{p}=\frac{x}{n}=\frac{492}{806}=0.61.$
b)$E=z_{\frac{\alpha}{2}}\cdot \sqrt{\frac{\hat{p}\cdot (1-\hat{p})}{n}}=2.575\cdot \sqrt{\frac{0.61\cdot (1-0.61)}{806}}=0.0442.$
c) Confidence interval: $\hat{p}-E
