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Unformatted text preview: The shading in the picture shows that on some positive percentage of days, ( x y ) < = x < y = Tamara sells less than Derek so while Tamara sells more than Derek on average , she does not sell more than Derek every day . B. Comparing Two Proportions 8.34 p 1 = proportion of all hightech companies which offer stock options p 2 = proportion of all nonhightech companies which offer stock options Sample Data n 1 = 91 x 1 = 73 b p 1 = 73 / 91 = . 8022 n 2 = 109 x 2 = 75 b p 2 = 75 / 109 = . 6881 Find a 95% confidence interval for ( p 1 p 2 ): (a) By formula: b p 1 b p 2 = s b p 1 (1 b p 1 ) n 1 + b p 2 (1 b p 2 ) n 2 = r ( . 8022)( . 1978) 91 + ( . 6881)( . 3119) 109 = . 0609 So a 95% confidence interval for ( p 1 p 2 ) is ( b p 1 b p 2 ) z * b p 1 b p 2 = ( . 8022 . 6881) (1 . 96)( . 0609) = . 1141 . 1194 = ( . 0053 to .2335) (b) By MINITAB : ( . 00530103 , . 233550) (c) Interpretation: We are 95% confident that between 0 . 53% fewer and 23.36% more high tech companies than nonhightechcompanies offer stock options. 8.36 1. p 1 = proportion of all hightech companies which offer stock options p 2 = proportion of all nonhightech companies which offer stock options H A : p 1 6 =...
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 Spring '07
 blake

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