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Find the margin of error if the braking distances of a simple random sample of 32 with...

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surfer3 | (Level 1) Valedictorian

Posted June 1, 2012 at 1:35 AM via web

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Find the margin of error if the braking distances of a simple random sample of 32 with σ equal to 7 ft lies in the 95% confidence interval.

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted June 2, 2012 at 2:50 PM (Answer #1)

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The margin of error is given by: ME = critical value*standard error. Standard error is `sigma/sqrt n` .

Here, sigma is known to be 7 ft. The number of samples is 32. This gives standard error as `7/sqrt 32 = 1.2374` . For the 95% confidence interval the critical value is 1.96. The margin of error is 1.96*1.2374 = 2.425

The margin of error is 2.425 and the confidence interval is 95%

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