Introduction Uncertainty of a quantity means that we cannot predicate its value in advance. A department store cannot exactly predicate the sales of a particular item on any given day; An airline cannot exactly predicate the number of people that will choose to fly on any given flight. How can these firms choose the number of items to keep in inventory or the number of flights to schedule on any given route? Based on the past experience for planning; Probability distribution is estimated based on historical data; Minimize expected cost or maximize the expected profit when uncertainty is present.Introduction Uncertainty of a quantity means that we cannot predicate its value in advance. • A department store cannot exactly predicate the sales of a particular item on any given day; • An airline cannot exactly predicate the number of people that will choose to fly on any given flight. How can these firms choose the number of items to keep in inventory or the number of flights to schedule on any given route? • Based on the past experience for planning; • Probability distribution is estimated based on historical data; • Minimize expected cost or maximize the expected profit when uncertainty is present