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Estimated proportion defective, 95% confidence interval

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 a 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.

Solution Preview

Please see the attached file.

a) Proportion of defective in the sample is
p=0.05
Hence estimated proportion of defective in the ...

Solution Summary

The expert estimates proportion defective with a 95% confidence interval.

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