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Unformatted text preview: that use paper and pencil. The percentage in calculator group is 18 / 250 100 = 7 . 2%, in the pencilandpaper group it is 59 / 250 100 = 23 . 6%. The SE for the number in the two groups is 250 . 072 . 928 = 4 . 08. The SE for the percentage is 4 . 08 / 250 100 = 1 . 63%. The SE for the number is 250 . 236 . 764 = 6 . 71. The SE for percentage is 6 . 71 / 250 100 = 2 . 68%. The SE for the dierence is 1 . 63 2 + 2 . 68 2 = 7 . 22%. The test statistic is z = 23 . 67 . 2 7 . 22 = 2 . 27. The Pvalue is 1%. This is highly signicant, so reject the null the dierence is real. 1...
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 Spring '11
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 Math, Statistics

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