Recall that the binomial distribution with parameters n, p, and r gives the probability distribution of the number of r successes in a sequence of n trials, each of which yields success with probability p. Here we can let "success" be defined as "finding a defective syringe." The batch contains 5% defective syringes, so there is a 5% chance that any given syringe will be found to be defective. Therefore, p = . A random sample of nine syringes are checked for quality, so n = .