Two suppliers manufacture a plastic gear used in a laser printer. The impact strength of these gears measured in foot-pounds is
an important characteristic. A random sample of 10 gears from supplier 1 results in $$\overline{\mbox{x}}_1=290$$ and $$s_1 = 12$$, and another random sample of 16 gears from the second supplier results in $$\overline{\mbox{x}}_2=321$$ and $$s_2 = 22$$.
a. Is there evidence to support the claim that supplier 2 provides gears with higher mean impact strength? Use α = 0.05, and assume that both populations are normally distributed but the variances are not equal.
What is the P-value for this test?
b. Do the data support the claim that the mean impact strength of gears from supplier 2 is at least 25 foot-pounds higher than that of supplier 1? Make the same assumptions as in part (a).
c. Construct a confidence interval estimate for the difference in mean impact strength, and explain how this interval could be used to answer the question posed regarding supplier-to-supplier differences.
a. Is there evidence to support the claim that supplier 2 provides gears with higher mean impact strength? Use α = 0.05, and assume that both populations are normally distributed but the variances are not equal.
What is the P-value for this test?
b. Do the data support the claim that the mean impact strength of gears from supplier 2 is at least 25 foot-pounds higher than that of supplier 1? Make the same assumptions as in part (a).
c. Construct a confidence interval estimate for the difference in mean impact strength, and explain how this interval could be used to answer the question posed regarding supplier-to-supplier differences.
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