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 2.4. The data (in micrometers) for 20 sampled pipe sections are reproduced in the accompanying table; a Minitab analysis of the data appears below.

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.

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1.72 2.50 2.16 2.13 2.57 2.64 1.26 2.05 1.19 2.13 1.27 1.51 2.41 1.95 1.06 2.24 2.31 2.03 1.09 1.40 One-Sample T: ROUGH Variable StDev SE Hean 20 1.88100 0.52391 0.11715 (1.63 500, 2.12620) 951 CI Hean ROUGH