3/28/2016 Chapter 7 Test 14. Quarters are currently minted with weights normally

Question

3/28/2016 Chapter 7 Test 14. Quarters are currently minted with weights normally distributed and having a standard deviation of 0.067. New equipment is being tested in an attempt to improve quality by reducing variation. A simple random sample of 23 quarters is obtained from those manufactured with the new equipment, and this sample has a standard deviation of 0.049. Use a 0.05 significance level to test the claim that quarters manufactured with the new equipment have weights with a standard deviation less than 0.067. Does the new equipment appear to be effective in reducing the variation of weights? (a) Write the claim mathematically and identify Ho and a OA. Hp o 20.067 (Claim); H: o

Explanation / Answer

(a) The right option is B.

(b) The cricial value is chisquare at 0.05 percentile with 22 degrees of freedom as 12.33801. The rejection region is given by A.

(c) The value of the chi-square statistic is 16.090.

(d) The null hypothesis is rejected.

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