week 5 etext problems

week 5 etext problems - exactly trapped or cut in the...

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8.46 A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on a very accurate scale. The results in grams were 3.087 3.131 3.241 3.241 3.270 3.353 3.400 3.411 3.437 3.477 (a) Construct a 90 percent confidence interval for the true mean weight. The standard error is E = 1.96(s/sqrt(n)) = 1.96[0.131989/sqrt(10)]=1.96*0.41739 =0.081808 C.I. = (x-bar-E,x-bar+E) = (3.3048-0.0818,3.3048+0.0818) (b) What sample size would be necessary to estimate the true weight with an error of ± 0.03 grams with 90 percent confidence? n=[z'*s/E]^2 n=[1.645*0.131989/0.03]^2 = 52.38; rounding up, n=53 Factors that can cause variation are whether air might be trapped inside and if the material is
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Unformatted text preview: exactly trapped or cut in the precise shape as the nature of the material has a slight stretch in it. 8.62 In 1992, the FAA conducted 86,991 pre-employment drug tests on job applicants who were to be engaged in safety and security-related jobs, and found that 1,143 were positive. p-hat = 1143/86991 = 0.013139 sigma = sqrt[p'q'/n'] = sqrt[0.013*0.0.987/86991]= 0.000384 (a) Construct a 95 percent confidence interval for the population proportion of positive drug tests. E = 1.96*0.000384 = 0.000753 95% C.I.: 0.013-0.000753 < p < 0.013 + 0.000753 95% C.I.: 0.0122 < p < 0.013763...
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