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Analysis of a random sample consisting of m = 20 specimens of cold-rolled steel to determine yield strengths resulted in

Posted: Thu Apr 28, 2022 7:41 am
by answerhappygod
Analysis of a random sample consisting of m = 20 specimens of
cold-rolled steel to determine yield strengths resulted in a sample
average strength of π‘₯ =29.8 ksi. A second random sample of n = 25
two-sided galvanized steel specimens gave a sample average strength
of 𝑦 =34.7 ksi. Assuming that the two yield-strength distributions
are normal with 𝜎1= 4.0 and 𝜎2= 5.0
(suggested by a graph in the article β€œZinc-Coated Sheet Steel: An
Overview,” Automotive Engr., Dec. 1984: 39–43), does the data
indicate that the corresponding true average yield strengths
πœ‡1 and πœ‡2 are different? Carry out
a test at significance level 𝛼= 0.01.