In each of the following, indicate what method of probability assessment would most likely be used to assess the probability.
a. What is the probability that a major earthquake will occur in California in the next three years?
b. What is the probability that a customer will return a purchase for a refund?
c. An inventory of appliances contains four white washers and one black washer. If a customer selects one at random, what is the probability that the black washer will be selected?