Spring 2011 Homework 10 - Probability and Statistics for...

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Probability and Statistics for Engineering Homework "! Spring 2011 (due Tuesday, April ) #' Many U.S. citizens get a tax refund in the spring. Out of this population, the proportion who put their : refunds into savings has, for many years, been %. An economist wonders if this proportion has #% changed. The economist obtains a random sample of U.S. citizens who got a tax refund this year, and 8 œ &!! finds that of them put their refunds into savings. "%! Following the steps below, perform a two-tailed hypothesis test. Use . ! œÞ!' (1) Set up the appropriate null and alternative hypotheses. (2) Find the point estimate . ^ : (3) Find the -value for the test. Be sure to show the set-up (exactly what probability you are T finding), at least one intermediate step, and a final numerical answer. (4) What should the economist conclude about the proportion this year who put their refunds into savings as compared to the proportion in the past?
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