6. Pregnancy and HIV Testing. A study examined the proportions of pregnant women in the United States who have had an HIV test in the past 12 months.¹¹ The proportions for the Northeast, Midwest, South, and West, resulting from four separate samples, were 56.8%, 49.3%, 58.5%, and 50.2%, respectively. Test whether the population proportions of pregnant women who have had an HIV test in the past 12 months are the same across all four regions, using level of significance . Assume that each sample size equals 1000.