Question 135910: I need help on this question this is part of a test. Does not show the text book instructor used.
3. An engineer in a widget factory wants to make a change to the process, and to switch to a cheaper supplier of the crucial raw material in the manufacture of widgets (that is, of course, widgeterium). It is important that the weight of the finished widgets not be different from the specified weight of 10 grams. A sample of 40 widgets created on a test run of the new material has an average weight of 10.8 grams, with a standard deviation of 2. Show work
a. Identify the null and alternative hypothesis
b. Calculate the proper test statistic
c. Calculate the proper P-value
d. In plain English, properly interpret the results, using a significance level of 0.05.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! An engineer in a widget factory wants to make a change to the process, and to switch to a cheaper supplier of the crucial raw material in the manufacture of widgets (that is, of course, widgeterium). It is important that the weight of the finished widgets not be different from the specified weight of 10 grams. A sample of 40 widgets created on a test run of the new material has an average weight of 10.8 grams, with a standard deviation of 2. Show work
a. Identify the null and alternative hypothesis
Ho: u=10
Ha: u is not 10
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b. Calculate the proper test statistic
z(40) = (10.8-10)/[2/sqrt(40)] = 2.53
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c. Calculate the proper P-value
p-value = P(2.53 < z < 10) = 0.005..
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d. In plain English, properly interpret the results,
using a significance level of 0.05.
Since p-value is less than sig level of 5%, Reject Ho.;
The test gives evidence that the mean weight of the
widgets made with the new material is not 10 grams.
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Cheers,
Stan H.
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