Stat 312 Homework Problems - Week 10

6 1236 ha y x 10 the p value is essentially zero so

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Unformatted text preview: I 1078 n 129 129 mean 107.6 123.6 Ha: Y - X > 10 . The p-value is essentially zero, so at any level of s 1.3 2.0 significance, we reject H0. The data overwhelmingly suggest that the mean tensile strength of the 1078 grade exceeds 2 the mean of the 1064 grade by more than 10 kg/mm . b. A 95% confidence interval for Y - X will provide information on precision and reliability. The confidence interval is given by . W e are 95% confident that the mean tensile strength of all 1078 gra de wire rods exceeds the mean tensile strength of the 1064 grade 2 wire rods by 15.59 to 16.41 kg/mm . 10. The data is summarized in the table. a. The hypotheses are H0: 1 - 2 = 5 The test statistic is versus Steel 1=High Purity 2=Commercial Ha: 1 - 2 > 5 . The p-value is n 32 38 1.2 1.1 mean 65.6 59.8 P(2.89 < Z) = 1 - .9981 = .0019. At the = .001 level of significance, we retain H0. The data do not provide sufficient evidence at the 0.1% level of significance that the mean toughness of the high purity steel exceeds the mean for the commercial grade by more than 5. b. 13. If we set = mean deflection for the steel beams and = mean deflection for the beams made wi...
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