The wall thickness of 25 glass 2-liter bottles was measured by a quality control
ID: 3221594 • Letter: T
Question
The wall thickness of 25 glass 2-liter bottles was measured by a quality control engineer. The sample mean was x bar = 4.058m and the sample standard was s = 0.081 mm. Sup m, deviation pose that it is important to demonstrate that the wall thickness exceeds 40 mm. Formulate and test appropriate hypotheses using these data. Write down the null and alternative hypotheses. Perform the test with alpha = 0.05. (Choose an appropriate direction to reflect the test) What are the assumptions to use the test in part (b)?Explanation / Answer
a)here null hypothesis: wall thickness mean <=4
alternate hypothesis:wall thickness mean >4
b)std error =std deviation/(n)1/2 =0.0162
hence test stat t=(X-mean)/std error =(4.058-4)/0.0162=3.58
at 0.05 level critical value of t =1.7109
as test stat is higher then critical value we reject null hypothesis and conclude that wall thickness exceeds 4 mm
c) we assume that sample follows normality as well the data has been picked with random sampling
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