A textile fiber manufacturer is investigating a new drapery

A textile fiber manufacturer is investigating a new drapery yarn, which the company claims has a mean thread elongation of 12 kilograms with a standard deviation of 0.5 kilograms. The company wishes to test the hypothesis H0: Mu = 12 against H1: Mu

Solution

(a) The degree of freedom =n-1=16-1=15

It is a left-tailed test.

Given a=0.03, the critical value is t(0.03, df=15)=-2.034 (from student t table)

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(b)The degree of freedom =n-1=16-1=15

It is a left-tailed test.

Given a=0.05, the critical value is t(0.05, df=15)=-1.753 (from student t table)

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(c)The degree of freedom =n-1=25-1=24

It is a left-tailed test.

Given a=0.03, the critical value is t(0.03, df=24)=-1.974 (from student t table)

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(d)The degree of freedom =n-1=25-1=24

It is a left-tailed test.

Given a=0.05, the critical value is t(0.05, df=24)=-1.711 (from student t table)