Question

2. In making aluminum castings into alternator housings, an average of 3.5 ounces per casting must be trimmed off and recycled as a raw material at the DAVID remanufacturing plant. A new manufacturing procedure has been proposed to reduce the amount of aluminum that must be recycled in this way. For a sample of 11 castings made with the new process the sample mean is 3.043 and sample standard deviation is 0.507. Using an appropriate hypothesis test, does the new manufacturing procedure appear to be effective? Assume that the ounces of castings are normally distributed. Let a = 0.01.

4. Data from the Office for National Statistics show that the mean age at which men in Great Britain get married is 30.8 years (The Guardian, February 15, 2013). A news reporter noted that this represents a continuation of the trend of waiting until a later age to wed. A new sample of 47 recently wed British men provided their age at the time of marriage. The sample mean is 32.7 and sample standard deviation is 12.1. Does this data indicate that the mean age of British men at the time of marriage exceeds the mean age in 2013? Test this hypothesis at a = 0.05.

6. An independent quality control consultant at the GYL inspection agency suspects that a pet food company may be mislabeling packages for one of its brands, i.e., the weights of the packages are not as stated. The package label states "1200 grams net weight," and the president of the company claims the true average weight is as stated. A sample of 14 packages has a sample mean of 1202.6 & sample standard deviation of 15.5. Using an appropriate hypothesis test, what conclusion should the agency reach in this situation? Assume that the weights of the packages are normally distributed. Let a = 0.05.

**FORM A NULL & ALTERNATE HYPOTHESIS**

Answer 1

Answer

(2) we want to test whether the new manufacturing process is effective or not, i.e. whether the mean is reduced or not. So, it is a left tailed hypothesis with population mean = 3.5

(4) we want to test whether the mean age of British men at time of marriage exceeds the mean age in 2013

mean age in 2013 is 30.8, it is a right tailed hypothesis

(6) we want to test whether the weight of packages are not as stated, i.e. the weight is either less or more than the stated weight. So, this is a two tailed hypothesis