Music Research Associates (MRA) is planning a study to estimate the difference in the average amount spent weekly on music download purchases by two different groups of consumers— teens under the age of 16 (Population1) and adults over the age of 30 (Population 2). MRA wants the interval estimate of the mean difference in purchases to show a margin of error of no more than + $.10 at the 90% confidence level. Assuming samples of equal size from the two populations (that is, n1 will equal n2), what sample sizes would be required here? A preliminary sample showed sample standard deviations of $ 1.23 for the Population1 sample and $ 2.04 for the Population 2 sample.
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