Chapter 22 - Inference about a Population Proportion - Chapter 22 Exercises - Page 534: 22.29b

.1574 to .1822

p = $\frac{x}{n}$ = $\frac{422}{2485}$ = .1698 $z_{a/2}$ = 1.645 p - $z_{a/2}$ $\times$ $\sqrt \frac{p(1-p)}{n}$ = .1698 - 1.645 $\times$ $\sqrt \frac{.1698(1-.1698)}{2485}$ = .1574 p - $z_{a/2}$ $\times$ $\sqrt \frac{p(1-p)}{n}$ = .1698 + 1.645 $\times$ $\sqrt \frac{.1698(1-.1698)}{2485}$ = .1822