ENGR 3302: Engineering Statistics and Experimentation Exam 3A- Fall 2017 Name nP

Question

ENGR 3302: Engineering Statistics and Experimentation Exam 3A- Fall 2017 Name nP-Mechanical EP-Physics (T Other My major is: EP-Electrical Biomedical Engr .This exam is closed book and closed note and closed computer . You may use an approved calculator and the attached formula sheet eyes on your own paper. You are not to collaborate with others in completing this exam Show all relevant work for full credit. Unsupported answers will receive zero credit Confidence intervals should show both "point estimate ± margin of error" and-int Do not discuss this exam with anyone until the exam is returned. . erval" (low, high) formats. . You have conducted surface roughness tests of the coated interiors of 34 pipes used in oil fields and found a mean of 1.86 microns and a standard deviation of 0.53 microns 1. a) State the appropriate thesis and alternate hypothesis that will allow you to determine whether the mean roughness is less than 2.00 microns. b) Compute the appropriate statistic and find the p-value c) What do you conclude based on this sample data?

Explanation / Answer

Given that
n = 34
mean = 1.86 and sd = 0.53

Ho: mean roughness is not less than 2 microns
H1 : mean roughness is less than 2 microns

we can conduct a t test using

t = (xbar-mu)/(sd/sqrt(n))
= (2-1.86)/(0.53/sqrt(34))
= 1.54

now we calculate df = n-1 = 34-1 = 33

also alpha = 0.05 , so we check the 1 tail test p value from the t table as
The P-Value is .066548.

The result is not significant at p < .05.
Hence we fail to reject the null hypothesis and conclude mean roughness is not less than 2 microns

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