Question

What is the approximate width of a 90 percent confidence interval for the true population proportion if there are 12 successes in a sample of 25? ± .480 ± .164 ± .206 ± .196?

Answer 1

$\hat{p}=\frac{12}{25}=0.48$
An approximate 90% confidence interval for the true population proportion p is given by:
$\hat{p}\pm 1.645 \sqrt{\frac{0.48(1-0.48)}{25}} =\hat{p}\pm0.164$
The correct choice of answer is the second one (b).