Question
The lifetime of a certain brand of electric light bulb is known to have a standard deviation of 55 hours. Suppose that a random sample
The lifetime of a certain brand of electric light bulb is known to have a standard deviation of 55 hours. Suppose that a random sample of 90 bulbs of this brand has a mean lifetime of 498 hours. Find a 99% confidence interval for the true mean lifetime of all light bulbs of this brand. Then complete the problems below.
Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place. (If necessary, consult a list of formulas.)
What is the lower limit of the 99% confidence interval?
What is the upper limit of the 99% confidence interval?
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Elementary Statisitcs
Authors: Barry Monk
2nd edition
1259345297, 978-0077836351, 77836359, 978-1259295911, 1259295915, 978-1259292484, 1259292487, 978-1259345296
