Question 594024
The Highway Safety Department wants to study the driving habits of individuals. A sample of 81 cars traveling on the highway revealed an average speed of 67 miles per hour with a standard deviation of 9 miles per hour.
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a. Compute the standard error of the mean.
standard error = 9/sqrt(81) = 1
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b. Determine a 99% confidence interval estimate for the speed of all cars.
Margin of error = 2.5758*[9/sqrt(81) = 2.5758
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99% CI: 67-2.5758 < u < 67+2.5758
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99%CI: 64.42 < u < 69.58
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