Schadek Silkscreen Printing, Inc., purchases plastic cups on which to print logos for sporting events, proms, birthdays, and other special occasions. Zack Schadek, the owner, received a large shipment this morning. To ensure the quality of the shipment, he selected a random sample of 330 cups. He found 12 to be defective.

a. What is the estimated proportion defective in the population? (Round the final answer to 3 decimal places.)

Estimated proportion defective

b. What are the endpoints of a 80% confidence interval for the proportion defective. (Round the final answers to 3 decimal places.)

Endpoints ,

c. Zack has an agreement with his supplier that he is to return lots that are 10% or more defective. Should he return this lot?

(Click to select) No, lot not 10% defective. Yes, 12 is outside the confidence interval. Yes, the lot is 10% defective.