Homework 7 Solutions - Homework 7 Chapter 10 Problem 3 Part...

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Homework 7 Chapter 10 Problem 3 Part of the assembly line will need adjusting if the consistency of the injected plastic becomes either too viscous or not viscous enough as compared with a value (56.00) your engineers consider reasonable. You will decide to adjust only if you are convinced that the system is “not in control,” i.e., there is a real need for adjustment. The average viscosity for 13 recent measurements was 51.22 with a standard error of 3.18. a. Identify the null and research hypotheses for a two-sided test, using both words and mathematical symbols. The null hypothesis, H 0 : μ = 56, claims that the population viscosity is equal to the reference value. The research hypothesis, H 1 : μ ≠ 56, claims that it is different. b. Perform a two-sided test at the 5% significance level and describe the result. Accept H 0 as a reasonable possibility. The viscosity of the system is not significantly different from 56. Using the confidence interval approach: X crit S t X ± X-bar = 51.22 S x-bar = 3.18 T-crit = 2.179 (95%, 12 d.f.) ) 18 . 3 179 . 2 ( 22 . 51 × ± The 95% confidence interval extends from 44.29 to 58.15 and includes the reference value (56.00). Using the t-statistic approach:
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Homework 7 Solutions - Homework 7 Chapter 10 Problem 3 Part...

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