Question: A June 2009 Gallup Poll asked a sample of Americans whether they trust specific groups or individuals when it comes to making recommendations about healthcare reform. Sixty percent of Democrats and 68% of Republicans stated that they trust doctors' opinions about healthcare reform (Source: https://www.gallup.com/poll/120890/Healthcare-Americans-Trust-Physicians-Politicians.aspx). Suppose this survey included 340 Democrats and 306 Republicans.
a. Make a 90% confidence interval for the difference in the population proportions for the two groups of people.
b. At the 5% significance level, can you conclude that the proportion of all Democrats who trust doctors' opinions about healthcare reform differs from the proportion of all Republicans who trust doctors' opinions about healthcare reform?