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quiz6Sp2011_key

# quiz6Sp2011_key - = 80 I ﬁnd t 025 = 1 990 • The...

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NAME: Stat 205 Quiz 6 A statistics professor polled his class on how much the students pay for a hair cut. The table below has summary statistics stratified by men and women on how much they typically pay (in \$). Formula (7.1) gives df = 84 . 7 . Construct and intepret a 95% confidence interval for the difference in means μ f - μ m where μ f is the average amount paid by women and μ m is the average amount paid by men. Female Male n 65 23 ¯ y 33.90 12.26 s 26.70 7.96 ANSWER : Using df
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Unformatted text preview: = 80 , I ﬁnd t . 025 = 1 . 990 . • The standard error of the difference in the sample means is se (¯ y 1-¯ y 2 ) = s s 2 1 n 1 + s 2 2 n 2 = r 26 . 70 2 65 + 7 . 96 2 23 = 3 . 704 . • The 95% CI is ¯ y 1-¯ y 2 ± t . 025 se (¯ y 1-¯ y 2 ) = 21 . 64 ± 1 . 990(3 . 704) = (14 . 27 , 29 . 01) . • With 95% conﬁdence, on average women pay between \$14.26 and \$29.01 more than men for a haircut/style....
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