Information for Problems 12 Prestressing wire for wrapping c

Information for Problems 1-2: Prestressing wire for wrapping concrete pipe is manufactured in large rolls. A quality control inspector required five specimens from a roll to be tested for ultimate tensile strength (UTS). The UTS measurements in 1000 psi produced a sample mean of 256.6 and a sample standard deviation of 3.05. It has been shown that UTS comes from a normally distributed population.

1.) Conduct a hypothesis test at the a=0.01 level of significance to determine if this sample comes from a population having a population mean UTS greater than 255. Include all 5 steps shown. (5 points)

a.) State the null and alternative hypotheses.

b.) Calculate the test statistic. Be sure to state whether the test statistic is a z or a t score.

c.) Calculate the p-value.

d.) What is your decision?

f.) Interpret your conclusion in the context of this problem.

2.) Calculate the corresponding lower one-sided confidence bound on the UTS. Briefly explain how this confidence interval is consistent with the results of the hypothesis test in problem 1. (5 points)

Solution