Question 300090: 4. Chicken Delight claims that 90 percent of its orders are delivered within 10 minutes of the time the order is placed. A sample of 100 orders revealed that 82 were delivered within the promised timeframe. At the 0.10 significance level, can we conclude that less than 90 percent of the orders are delivered in 10 minutes or less?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Chicken Delight claims that 90 percent of its orders are delivered within 10 minutes of the time the order is placed.
A sample of 100 orders revealed that 82 were delivered within the promised timeframe.
At the 0.10 significance level, can we conclude that less than 90 percent of the orders are delivered in 10 minutes or less?
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Ho: p = 0.90 (claim)
Ha: p < 0.90
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sample proportion: 0.82
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test statistic: z(0.82) = (0.82-0.90)/sqrt[0.9*0.1/100] = -2.667
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critical values: z = +-1.645
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Conclusion: Since the ts is in the reject interval, reject Ho.
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Cheers,
Stan H.
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