A national manufacturer of ball bearings is experimenting with two different pro
ID: 3330857 • Letter: A
Question
A national manufacturer of ball bearings is experimenting with two different processes for producing precision ball bearings. It is important that the diameters be as close as possible to an industry standard. The output from each process is sampled and the average error from the industry standard is measured in millimeters. The results are presented here. Process A Process B Sample mean 2.0 3.0 Standard deviation 1.0 0.5 Sample size 12 14 The researcher is interested in determining whether there is evidence that the two processes yield different average errors. The population standard deviations are unknown but are assumed equal. What is the computed value of t? Multiple Choice +2.797 1.000 3.299 0.5938
Explanation / Answer
The statistical software output for this problem is:
Two sample T summary hypothesis test:
1 : Mean of Population 1
2 : Mean of Population 2
1 - 2 : Difference between two means
H0 : 1 - 2 = 0
HA : 1 - 2 0
(with pooled variances)
Hypothesis test results:
Hence,
Test statistic = -3.299
Option C is correct.
Difference Sample Diff. Std. Err. DF T-Stat P-value 1 - 2 -1 0.30313344 24 -3.2988772 0.003Related Questions
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