Fewer young people are driving. In 1983, 87% of 19-year-olds had a driver's license. Twenty-five years later that percentage had dropped to 75% (University of Michigan Transportation Research Institute website, April 7, 2012). Suppose these results are based on a random sample of 1200 19-year-olds in 1983and again in 2008. a. At 95% confidence, what is the margin of error and the internal estimate of the number of 19-year old drivers in 19SS? b. At 95 6 confidence, what is the margin of error and the interval estimate of the number of 19-year old drivers in 2008? c.Is the margin of error the same in parts (a) and (b)? Why or why not?

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2-Proportion Test

In a 2-proportion test, two separate proportions are measured at the same time, and their similarity is evaluated. It is also known as a 2-proportion z-test, and a comparison of two different proportions is done in this method.