Quality control: the quality control director of a small company that manufactures exercise equipment knows that 10% of their products are defective. market research shows that only 30% of their customers will use the product in the first year after the sale. so, the manufacturer expects that 3% of the units will be returned for service under a one-year full warranty. this company expects to sell 600 units next year. (hint: write down what you know from the problem) a) describe the sampling distribution of , the proportion of the 600 units that will be returned for service.