A random sample of 432 voters revealed that 100 are in favor of a certain bond issue. A 95 percent confidence interval for the proportion of the population of voters who are in favor of the bond issue is

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A 95 percent confidence interval corresponds to a critical value of 1.96.

The estimate for the population proportion is:

$$ \hat{p} = \frac{100}{432} = 0.231$$

The confidence interval is:

$$ \hat{p} \pm \text{critical value}\left(\sqrt{\frac{\hat{p}(1-\hat{p})}{n}}\right) $$ $$ =0.231\pm 1.96\sqrt{\dfrac{0.231(0.769)}{432}} $$