2. Methods for Proportions and Nominal Variables [10 points) [a] In an attempt to encourage more at-risk individuals to get tested for blood-borne viruses and sexually transmitted infections [STIs], a public health group devised an ad campaign touting the benefits and importance of getting tested. Before unveiling the campaign nationwide, they wanted to evaluate its efficacy by testing it on 172 volunteer subjects. The subjects were either shown the ad campaign or allowed to browse the internet for 10 minutes, then were asked whether or not they were willing to get tested; the results are summarized in the table below. Willing to get tested Not willing to get tested Not shown ad campaign Use a z-test to determine if there is a significant difference in the proportions of the subjects willing to be tested between the two groups