An automobile manufacturer claims his best product has an average lifespan of exactly 20 years. A skeptical pr

An automobile manufacturer claims his best product has an average lifespan of exactly 20 years. A skeptical product evaluator asks for evidence (data) that might be used to evaluate this claim. The product evaluator was provided data collected from a random sample of 45 people who used the product. Using the data, an average product lifespan of 21 years and a standard deviation of 8 years was calculated. Select the 99%, confidence interval for the true mean lifespan of this product. Use the appropriate table in your book.a) [17.422, 24.578]
b) [16.923, 23.077]
c) [-3.0769, 3.0769]
d) [20.541, 21.459]
e) [17.923, 24.077]
f) None of the above

99% confidence interval for population mean (Mu) is
sample mean +/- z-score for 99% confidence*standard deviation/sqrt sample size
21 +/- 2.58*8/sqrt 45
21 +/- 3.077
lower limit is 21 - 3.077 = 17.923
upper limit is 21 + 3.077 = 24.077
The CI is (17.923, 24.077)

CHOICE (e) is the answer...