Understanding Basic Statistics 6th Edition by Charles Henry Brase,Corrinne Pellillo Brase

Exercise 18

For Problems 3-11, please provide the following information:
(a) What is the level of significance State the null and alternate hypotheses.
(b) Find the value of the chi-square statistic for the sample. What are the degrees of freedom Check Requirements What assumptions are you making about the original distribution
(c) Find or estimate the P -value of the sample test statistic.
(d) Based on your answers in parts (a)-(c), will you reject or fail to reject the null hypothesis of independence
(e) Interpret your conclusion in the context of the application.
In each of the following problems, assume a normal population distribution.
Engineering: Jet Engines The fan blades on commercial jet engines must be replaced when wear on these parts indicates too much variability to pass inspection. If a single fan blade broke during operation, it could severely endanger a flight. A large engine contains thousands of fan blades and safety regulations require that variability measurements on the population of all blades not exceed 2 = 0.18 mm 2. An engine inspector took a random sample of 61 fan blades from an engine. She measured each blade and found a sample variance of 0.27 mm 2. Using a 0.01 level of significance, is the inspector justified in claiming that all the engine fan blades must be replaced