The managers at Hunter Chemical Company claim that their major product contains on average ? = 4.0 fluid ounces of caustic material per gallon. They further state that the distribution of caustic material content per gallon is normal with a standard deviation o f? = 1.3 fluid ounces. If there is too much caustic material, the product will be dangerous. A government inspector is brought in to test the product. She randomly selects a sample of 100, gallon-size containers of the product and finds that their mean weight of caustic materials is