Question

The deterioration of many municipal pipeline networks across the country is a growing concern. One technology proposed for pipeline rehabilitation uses a flexible liner threaded through existing pipe.

The article "Effect of Welding on a High-Density Polyethylene Liner" (J. of Materials in Civil Engr., 1996: 94-100) reported the following data on tensile strength (psi) of liner specimens when a certain fusion process was used and when this process was not used.
No Fusion :: 2748 2700 2655 2822 2511 3149 3257 3213 3220 2753
Yes Fusion :: 3027 3356 3359 3297 3125 2910 2889 2902
Compare the mean tensile strengths at the 95% confidence level ...
Perform a COMPLETE APPROPRIATE analysis.
Answer the question of interest, check assumptions, etc.

Answer 1

To compare the mean tensile strengths at the 95% confidence level, we perform a two-sample t-test. The calculated t-value is compared to the critical t-value from the t-distribution table. The null hypothesis is not rejected, indicating no significant difference in mean tensile strengths.

Step-by-step explanation:

To compare the mean tensile strengths at the 95% confidence level, we need to perform a hypothesis test. The null hypothesis (H0) is that there is no difference in the mean tensile strengths between the no fusion and yes fusion processes. The alternative hypothesis (Ha) is that there is a difference in the mean tensile strengths.

Finally, we compare the t-value to the critical t-value from the t-distribution table. For a 95% confidence level with 15 degrees of freedom (n1 + n2 - 2), the critical t-value is approximately 2.131. Since the calculated t-value (-1.8073) is less than the critical t-value (2.131), we fail to reject the null hypothesis. Therefore, we conclude that there is not enough evidence to suggest a significant difference in the mean tensile strengths between the no fusion and yes fusion processes at the 95% confidence level.