A researcher is going to perform a significance test for the difference between two population proportions (H_{0} : p_{1} = p_{2}) based on the following sample statistics:X_{1} = 12,n_{1} = 20,X_{2} = 15,n_{2} = 30. Which of the following would be used to compute the value of z for this test?  

2.  A random sample of 384 people in Dalto City, a midsized city, revealed 112 individuals who work at more than one job. A second random sample of 432 workers from East Dettweiler, another midsized city, found 91 people who work at more than one job. To conduct a significance test for a difference in the proportions of workers in Dalto City and East Dettweiler who work at more than one job, what’s the pooled value for p?, and what’s the pooled standard error of the difference between the two sample proportions, respectively?  

3.  Consider the following data collected in two recent surveys of whether voters in cities A and B favor a ballot proposition in the next election.
Suppose you’re going to conduct a significance test to see if there’s a difference between the two population proportions. What’s the standard error of the estimate? 


4.  A random sample of 250 men yielded 175 who said they’d ridden a motorcycle at some time in their lives, while a similar sample of 215 women yielded only 43 that had done so. Find a 99% confidence interval for the difference between the proportions of men and women who have ridden motorcycles.  
