SOLUTION: The breaking strengths of cables produced by a certain manufacturer have a standard deviation of 94 pounds. A random sample of 80 newly manufactured cables has a mean breaking stre

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Question 1159555: The breaking strengths of cables produced by a certain manufacturer have a standard deviation of 94 pounds. A random sample of 80 newly manufactured cables has a mean breaking strength of 1800 pounds. Based on this sample, find a 99% confidence interval for the true mean breaking strength of all cables produced by this manufacturer. 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 the 99% confidence interval?

What is the upper limit of the 99% confidence interval?

Answer by Boreal(15235) (Show Source):
You can put this solution on YOUR website!
99% CI for mean is sample mean+/- z(0.995)*sigma/sqrt(n)
half-interval is 2.576*94/sqrt(80)
=27.07 or 27.1 pounds
99%CI is (1772.9, 1827.1) pounds, the lower and the upper limit respectively