SOLUTION: The Better Business Bureau settles 75% of complaints it receives involving new car dealers. Suppose a sample of 160 complaints involving new car dealers is selected.
Find the pr
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Question 1124583: The Better Business Bureau settles 75% of complaints it receives involving new car dealers. Suppose a sample of 160 complaints involving new car dealers is selected.
Find the probability that Better Business Bureau settles less than 129 of these complaints. Answer by rothauserc(4718) (Show Source):
You can put this solution on YOUR website! mean is 0.75
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we do not know the standard deviation of the population, so we will use the standard error
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standard error = square root(0.75 * (1-0.75) / 160) = 0.0342
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the sample size is greater than 30, so we can use the normal distribution
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129/160 is approximately 0.8062
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we want the probability that X is less than 0.8062
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z-score = (0.8062 - 0.75)/0.0342 is approximately 1.64
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using table of z-scores, we find the probability associated with z-score of 1.64
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Probability ( X < 0.8062 ) = 0.9495
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