The tensile strength of a metal is a measure of its ability to resist tearing when it is pulled lengthwise. A new experimental type of treatment produced steel bars with the tensile strengths (in newtons per square millimeter) listed below.

Experimental Method:

The old method produced steel bars with the tensile strengths (in newtons per square millimeter) listed below.

Old Method:

At α = 0.01, can you support the claim that the new treatment makes a difference in the tensile strength of steel bars? Assume the population variances are equal.

(a) Identify the claim and state H₀ and H_a,

(b) Find the critical value(s) and identify the rejection region(s),

(c) Find the standardized test statistic t,

(d) Decide whether to reject or fail to reject the null hypothesis,

(e) Interpret the decision in the context of the original claim. Assume the samples are random and independent, and the populations are normally distributed. If convenient, use technology.

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