Assume a river's alkalinity level is normally distributed with mean 50 milligrams per liter and standard deviation 3.2 milligrams per liter.
a) What is the probability that a river's alkalinity level is greater than 48.4 milligrams per liter?
b) Suppose a random sample of 6 rivers is selected and the alkalinity level of each is measured. What is the probability that the random sample mean will be greater than 48.4 milligrams per liter?
c) Suppose a random sample of 6 rivers is selected and the alkalinity level of each is measured. What is the probability that the random sample mean will equal 48.4 milligrams per liter?