Question

Tensile-strength tests were carried out on two different grades of wire rod ("Fluidized Bed Patenting of Wire Rods," Wire J., June 1977: 56–61), resulting in the accompanying data. Grade Sample Size Sample Mean (kg/mm²) Sample SD AISI 1064 m = 129 x? = 107.6 s? = 1.3 AISI 1078 n = 129 y? = 123.6 s? = 2.0 a. Does the data provide compelling evidence for concluding that true average strength for the 1078 grade exceeds that for the 1064 grade by more than 10 kg/mm²? Test the appropriate hypotheses using a significance level of .01. b. Estimate the difference between true average strengths for the two grades in a way that provides information about precision and reliability.

          Tensile-strength tests were carried out on two different grades of wire rod ("Fluidized Bed Patenting of Wire Rods," Wire J., June 1977: 56–61), resulting in the accompanying data.

Grade Sample Size Sample Mean (kg/mm²) Sample SD
AISI 1064 m = 129 x? = 107.6 s? = 1.3
AISI 1078 n = 129 y? = 123.6 s? = 2.0

a. Does the data provide compelling evidence for concluding that true average strength for the 1078 grade exceeds that for the 1064 grade by more than 10 kg/mm²? Test the appropriate hypotheses using a significance level of .01.
b. Estimate the difference between true average strengths for the two grades in a way that provides information about precision and reliability.

Tensile-strength tests were carried out on two different grades of wire rod ("Fluidized Bed Patenting of Wire Rods," Wire J., June 1977: 56–61), resulting in the accompanying data.

Grade Sample Size Sample Mean (kg/mm²) Sample SD
AISI 1064 m = 129 x? = 107.6 s? = 1.3
AISI 1078 n = 129 y? = 123.6 s? = 2.0

a. Does the data provide compelling evidence for concluding that true average strength for the 1078 grade exceeds that for the 1064 grade by more than 10 kg/mm²? Test the appropriate hypotheses using a significance level of .01.
b. Estimate the difference between true average strengths for the two grades in a way that provides information about precision and reliability.

Added by Ricky B.

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