A lot of parts contains 500 items, 100 of which are defective. Suppose that 20 items are selected at random. Let X be the number of selected items that are defective. a) Express the quantity P(X = 5)...

A lot of parts contains 500 items, 100 of which are defective. Suppose that 20 items are selected at random. Let X be the number of selected items that are defective. a) Express the quantity P(X = 5) using factorials. b) Use the binomial approximation to compute an approximation to P(X = 5).