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Unformatted text preview: 5E Exam 3 practice Formulas at end are as they will be on exam. For any hypothesis test, clearly state null and alternative hypotheses. 1. Let 1 =the mean for and 2 =the mean for . H : 1 2 0 or 2 1 0 (Ill use the first in my calculations.) H a : 1 2 > 0 or 2 1 < To find the standard error and degrees of freedom Ill first calculate s 2 1 /n 1 and s 2 2 /n 2 . These are 20 2 / 70 = 5 . 714 and 23 2 / 70 = 7 . 557. So the standard error is p ( s 2 1 n 1 + s 2 2 n 2 = 5 . 714 + 7 . 557 = 3 . 643. The t statistic for the data is then t = (160 152) 3 . 643 = 2 . 196. At this point we need to compare that t value with one from the table. To do so we need the degrees of freedom. According to the formula it is df = (5 . 714+7 . 557) 2 1 69 5 . 714 2 + 1 69 7 . 557 2 = 135 . 4. We dont find this exact df in the table, but comparison with df = 120 and df = 140 indicates a P value of just under 2%. So reject H in favor of H a : The data does provide...
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 Fall '08
 LANDRIGAN

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