SOLUTION: 4. 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 wi

Algebra ->  Probability-and-statistics -> SOLUTION: 4. 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 wi      Log On


   

Question 594024: 4. 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.
a. Compute the standard error of the mean.
b. Determine a 99% confidence interval estimate for the speed of all cars.
Answer by stanbon(75887) About Me  (Show Source):
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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