Question 1193144: A publisher wants to estimate the mean length of time (in minutes) all adults spend reading newspapers. To determine this estimate, the publisher takes a random sample of 15 people and obtains the results below. From past studies, the publisher assumes sigma is 1.7 minutes and that the population of times is normally distributed.
11 6 6 11 7 9 8 9 12 6 10 7 8 9 9
Construct the 90% and 99% confidence intervals for the population mean. Which interval is wider? If convenient, use technology to construct the confidence intervals. The 90% confidence interval is ___ (Round to one decimal place as needed)
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! mean is 128/15=8.467
use pop sd of 1.7
90% CI is (7.74, 9.18) min or (7.7, 9.2)
99% CI is (7.33, 9.59) min or (7.3, 9.6)
The higher confidence interval is wider consistent with higher confidence requiring a larger interval.
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