Single-sample acceptance sampling for attributes uses a procedure similar to that of Exercise 19. Suppose that a sampling plan for accepting a lot of size N coming to a manufacturer from a supplier is to be determined by sampling items from the lot and accepting the entire lot if c of fewer of the items are defective. The lot fraction defective, p, is the true proportion of defective items in the lot. The probability of observing defective items in a random sample of items can be calculated using the binomial distribution. The probability of observing c or fewer defective items is the sum of the probabilities from 0 to c and is called the probability of acceptance, Pa. An operating characteristic (OC) curve is then constructed plotting Pa versus p. This OC curve illustrates the performance of a sampling plan using n items and an acceptance value of c. Construct an OC curve for the sampling plan n = 50 and c = 1. OC curves are further discussed in Section 3.2.