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Get Full Access to Statistics For Engineers And Scientists - 4 Edition - Chapter 5.4 - Problem 11e
Get Full Access to Statistics For Engineers And Scientists - 4 Edition - Chapter 5.4 - Problem 11e

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# In a study of the effect of cooling rate on the hardness

ISBN: 9780073401331 38

## Solution for problem 11E Chapter 5.4

Statistics for Engineers and Scientists | 4th Edition

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Problem 11E

Problem 11E

In a study of the effect of cooling rate on the hardness of welded joints, 50 welds cooled at a rate of 10 ºC/s had an average Rockwell (B) hardness of 91.1 and a standard deviation of 6.23, and 40 welds cooled at a rate of 30°C/s had an average hardness of 90.7 and a standard deviation of 4.34.

a. Find a 95% confidence interval for the difference in hardness between welds cooled at the different rates.

b.Someone says that the cooling rate has no effect on the hardness. Do these data contradict this claim? Explain.

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In a study of the effect of cooling rate on the hardness