Two companies manufacture a rubber material intended for use in an automotive application. The part will be subjected to abrasive wear in the field application, so we decide to compare the material produced by each company in a test. Twenty-five samples of material from each company are tested in an abrasion test, and the amount of wear after 1000 cycles is observed. For company 1, the sample mean and standard deviation of wear are ?̅1 = 20 milligrams/1000 cycles and ?1 = 2 milligrams/1000 cycles, while for company 2 we obtain ?̅2 = 15 milligrams/1000 cycles and ?2 = 8 milligrams/1000 cycles. [taken from Montgomery, p. 348] (a) Do the data support the claim that the two companies produce material with
Two companies manufacture a rubber material intended for use in an automotive
application. The part will be subjected to abrasive wear in the field application, so we
decide to compare the material produced by each company in a test. Twenty-five samples of material from each company are tested in an abrasion test, and the amount
of wear after 1000 cycles is observed. For company 1, the sample mean and standard
deviation of wear are ?̅1 = 20 milligrams/1000 cycles and ?1 = 2 milligrams/1000
cycles, while for company 2 we obtain ?̅2 = 15 milligrams/1000 cycles and ?2 = 8
milligrams/1000 cycles. [taken from Montgomery, p. 348]
(a) Do the data support the claim that the two companies produce material with
different mean wear? Use ? = 0.05, and assume each population is
distributed
(b)What is the ?-value for this test?
(c) Do the data support a claim that the material from company 1 has a higher mean
wear than the material from company 2? Use the same assumptions as in part (a).
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