A market research firm is hired to estimate the percent of adults living in a large city who have cell phones. Five hundred randomly selected adult residents in this city are surveyed to determine...

A market research firm is hired to estimate the percent of adults living in a large city who have cell phones. Five hundred randomly selected adult residents in this city are surveyed to determine whether they have cell phones. Of the 500 people surveyed, 430 responded "yes, they own cell phones."

Using a 90% confidence level, compute a confidence interval estimate for the true proportion of adult residents of this city who have cell phones.