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 300 cups. He found 15 to be defective.
a. What is the estimated proportion defective in the population?
b. Develop a 95% confidence interval for the proportion defective.
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? Explain your decision.