Two-sample Proportions: Confidence Intervals and Hypothesis Testing, Exams of Probability and Statistics

Download Two-sample Proportions: Confidence Intervals and Hypothesis Testing and more Exams Probability and Statistics in PDF only on Docsity! Two-sample proportion procedures worksheet 1) Covariant Industries outsources its paperwork imaging needs to two companies: Endomorphism Inc. and Tensor Limited. The paperwork coordinator is curious which company is better at getting documents onto the imaging system within 24 hours. She selects an SRS of documents sent to each company and determines how many of these documents were placed in the imaging system within 24 hours. Here are the results of the study: Company Documents proccessed within 24 hours Documents in sample Endomorphism Inc. 249 515 Tensor Limited 125 218 a) Find a 95% confidence interval for the difference between the proportion of documents processed within 24 hours by Endomorphism Inc. and the proportion for Tensor Limited. b) Is there significant evidence, at the 5% level, that the proportions of documents processed within 24 hours by Endomorphism Inc. is different than the proportion for Tensor Limited? (Hint: you can carry out this significance test by using the interval above.) 2) A political polling firm is interested in differences in voting behavior between men and women. They conduct an SRS of registered voters, ask them how they plan to vote in an upcoming election between R. Green and J. Bleau, and get the following results: Sex R. Green J. Bleau Undecided Male 305 328 41 Female 410 329 31 a) Find a 99% confidence interval for the difference between the proportion of all male voters voting for Green and the proportion of all female voters voting for Green. b) Find a 99% confidence interval as above, but this time only consider voters who have made a decision. (In other words, throw out undecided voters.) 1