Question: A package-filling device is set to fill cereal boxes with a mean weight of 20 ounces of cereal per box. The sample standard deviation of the amount actually put into the boxes is 0.5 ounces. A random sample of 16 filled boxes is weighed, yielding a mean weight of 20.32 ounces. Test at the 0.05 significance level to determine whether the device is working properly.