Researchers investigating groundwater are interested in soil porosity, which is affected by the size of individual grains of soil. Suppose that at a particular site the diameters of indivdual grains of soil have a Normal distribution with a mean of 1.33 mm and a variance of 0.0040. If a random sample of n = 30, grains is selected
Find the probabilty that the sample mean Ybar is between 1.32 mm and 1.34 mm.