SOLUTION: The lifetime of a certain brand of battery is known to have a standard deviation of 9 hours. Suppose that a random sample of 100 such batteries has a mean lifetime of 45.6 hours.

Question 135935: The lifetime of a certain brand of battery is known to have a standard deviation of 9 hours. Suppose that a random sample of 100 such batteries has a mean lifetime of 45.6 hours. Based on this sample, find a 95% confidence interval for the true mean lifetime of all batteries of this brand. Then complete the table below.
Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place.

What is the lower limit of 95% confindence interval?
What is the upper limit of 95% confindence interval?

Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
The lifetime of a certain brand of battery is known to have a standard deviation of 9 hours. Suppose that a random sample of 100 such batteries has a mean lifetime of 45.6 hours. Based on this sample, find a 95% confidence interval for the true mean lifetime of all batteries of this brand. Then complete the table below.
Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place.
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x-bar = 45.6
E = 1.96 = 2.178
What is the lower limit of 95% confindence interval? 45.6-2.178
What is the upper limit of 95% confindence interval? 45.6+2.178
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Cheers,
Stan H.

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