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Surface roughness of pipe. Refer to the Anti-corrosion
Chapter 6, Problem 33E(choose chapter or problem)
Problem 33E
Surface roughness of pipe. Refer to the Anti-corrosion Methods and Materials (Vol. 50, 2003) study of the surface roughness of coated interior pipe used in oil fields, Exercise 2.44 (p. 70). The data (in micrometers) for 20 sampled pipe sections are reproduced in the accompanying table; a Minitab analysis of the data appears below
1.72 |
2.50 |
2.16 |
2.13 |
1.06 |
2.24 |
2.31 |
2.03 |
1.09 |
1.40 |
2.57 |
2.64 |
1.26 |
2.05 |
1.19 |
2.13 |
1.27 |
1.51 |
2.41 |
1.95 |
Source: Data from Farshad, F., & Pesacreta, T. “Coated pipe interior surface roughness as measured by three scanning probe instruments,” Anti-corrosion Methods and Materials, Vol. 50, No. 1, 2003 (Table III).
a. Locate a 95% confidence interval for the mean surface roughness of coated interior pipe on the accompanying Minitab printout.
b. Would you expect the average surface roughness to be as high as 2.5 micrometers? Explain.
Questions & Answers
QUESTION:
Problem 33E
Surface roughness of pipe. Refer to the Anti-corrosion Methods and Materials (Vol. 50, 2003) study of the surface roughness of coated interior pipe used in oil fields, Exercise 2.44 (p. 70). The data (in micrometers) for 20 sampled pipe sections are reproduced in the accompanying table; a Minitab analysis of the data appears below
1.72 |
2.50 |
2.16 |
2.13 |
1.06 |
2.24 |
2.31 |
2.03 |
1.09 |
1.40 |
2.57 |
2.64 |
1.26 |
2.05 |
1.19 |
2.13 |
1.27 |
1.51 |
2.41 |
1.95 |
Source: Data from Farshad, F., & Pesacreta, T. “Coated pipe interior surface roughness as measured by three scanning probe instruments,” Anti-corrosion Methods and Materials, Vol. 50, No. 1, 2003 (Table III).
a. Locate a 95% confidence interval for the mean surface roughness of coated interior pipe on the accompanying Minitab printout.
b. Would you expect the average surface roughness to be as high as 2.5 micrometers? Explain.
ANSWER:
Answer
Step 1 of 2
(a)
The data (in micrometers) for 20 sampled pipe sections are reproduced in the accompanying table; a Minitab analysis of the data appears below.
1.72 |
2.5 |
2.16 |
2.13 |
1.06 |
2.24 |
2.31 |
2.03 |
1.09 |
1.4 |
2.57 |
2.64 |
1.26 |
2.05 |
1.19 |
2.13 |
1.27 |
1.51 |
2.41 |
1.95 |
We are asked to locate a confidence interval for the mean surface roughness of coated interior pipe on the accompanying Minitab printout.
Step to create the descriptive measures in Minitab:
- On the opening of Minitab, you will get session handler and worksheet like Excel worksheet.
- Enter the data into the worksheet (in this case pipe sections ).
- After entering the data go to menu called Stat in menu panel and under that select Basic Statistics option.
- In drop down menu of Basic Statistics option, select 1-Sample t.
- After clicking you will get the summary of mean, confidence interval etc.
From the accompanying Minitab printout, we can see that our confidence interval for the mean surface roughness of coated interior pipe is