The article Evaluating Tunnel Kiln Performance (Amer.
Chapter 7, Problem 7.14(choose chapter or problem)
The article Evaluating Tunnel Kiln Performance (Amer. Ceramic Soc. Bull., Aug. 1997: 5963) gave the following summary information for fracture strengths (MPa) of n 169 ceramic bars fired in a particular kiln: x 89.10, s 3.73. a. Calculate a (two-sided) confidence interval for true average fracture strength using a confidence level of 95%. Does it appear that true average fracture strength has been precisely estimated? b. Suppose the investigators had believed a priori that the population standard deviation was about 4 MPa. Based on this supposition, how large a sample would have been required to estimate to within .5 MPa with 95% confidence?
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