statistics question

Question

According to a poll, 80% of California adults (406 out of 506 surveyed) feel that education is one of the top issues facing California. We wish to construct a 90% confidence interval for the true proportion of California adults who feel that education is one of the top issues facing California.

What is a point estimate for the true population proportion?

Answer 1

sample proportion phat = 0.80

sample size (n) = 506

z-critical for 90% CI = 1.645

phat is the point estimate for the population proportion

plug values into following formula for confidence interval (CI)

CI = phat +/- z-critical * sqrt(phat*(1-phat)/n)