<PRE><B>Question 135935</B>
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*[9/sqrt(100)] = 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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