Iodine is an important nutrient for the human body, especially in hormone development. Milk is a natural source of iodine, and the mean amount in cow’s milk is 88 mg/250ml. 24 Milk from organic farms...

Iodine is an important nutrient for the human body, especially in hormone development. Milk is a natural source of iodine, and the mean amount in cow’s milk is 88 mg/250ml. 24 Milk from organic farms is reported to have a lower concentration of elements such as zinc, iodine, and selenium. A random sample of 35 gallons of organic milk from Humboldt County, California, was obtained and the iodine concentration was measured in each. The sample mean was x = 86.5. Assume s = 3.4. Is there any evidence to suggest that the mean iodine concentration in organic milk is less than 88? Use a = 0.01.

The four parts of a hypothesis test concerning a population mean from a normal population are shown below.