Question

In: Statistics and Probability

The breaking strength of yarn supplied by two manufacturers is being investigated. We know from experience...

The breaking strength of yarn supplied by two manufacturers is being investigated. We know from experience with the manufacturers’ processes that σ1 = 5 psi and σ2 = 4 psi. A random sample of 20 test specimens from each manufacturer results in x¯1 = 88 psi and x¯2 = 91 psi.

(a) Show all steps (including how to find cutoff value) and construct a two-sided 90% Confidence Interval for the true difference in means. Draw a conclusion on whether yarn 1 and yarn 2 are significantly different using only the confidence interval constructed.

(b) Show all steps (including how to find cutoff value) and construct a two-sided 95% Confidence Interval for the true difference in means. Draw a conclusion on whether yarn 1 and yarn 2 are significantly different using only the confidence interval constructed.

Solutions

Expert Solution

( a )

yarn 1 and yarn 2 are significantly different because 0 does not lies between -5.355 and -0.645

( b )

yarn 1 and yarn 2 are significantly different  because 0 does not lies between -5.806 and -0.194

orchestra answered 1 year ago
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