Question: In problem, give a 95% confidence interval for the increase in the population proportion of consumers preferring California wines following the campaign.
Problem: A random sample of 2,060 consumers shows that 13% prefer California wines. Over the next three months, an advertising campaign is undertaken to show that California wines receive awards and win taste tests. The organizers of the campaign want to prove that the three-month campaign raised the proportion of people who prefer California wines by at least 5%. At the end of the campaign, a random sample of 5,000 consumers shows that 19% of them now prefer California wines. Conduct the test at α = 0.05.