SOLUTION: "A random sample of 80 cell phones was inspected in a cell phone factory. It was found that 6 of the cell phone is defective in some way. Based on this data, the auditor wants to p

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Question 321107: "A random sample of 80 cell phones was inspected in a cell phone factory. It was found that 6 of the cell phone is defective in some way. Based on this data, the auditor wants to perform a statistical test to see that the defective rate of cell phone produced by the factory is greater than 5%."

Answer by stanbon(75887) (Show Source):
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"A random sample of 80 cell phones was inspected in a cell phone factory.
It was found that 6 of the cell phones is defective in some way. Based on this data, the auditor wants to perform a statistical test to see that the defective rate of cell phone produced by the factory is greater than 5%."
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Ho: p <= 0.05
Ha: p > 0.05 (claim)
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sample proportion: 6/80 = 0.075
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Test statistic: z(0.075) = (0.075-0.05)/sqrt(0.05*0.95/80) = 1.0260
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p-value: P(z > 1.0260) = 0.1525
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Conclusion: Since the p-value is greater than 5%, fail to reject Ho.
The test does not support the auditor's conjecture.
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Cheers,
Stan H.