SOLUTION: In order to estimate the average daily down time, a manufacturer randomly sampled 41 days of production records and found a mean of 51.75 minutes and standard deviation of 7.9 minu

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Question 1059126: In order to estimate the average daily down time, a manufacturer randomly sampled 41 days of production records and found a mean of 51.75 minutes and standard deviation of 7.9 minutes. A 90% confidence interval for the population mean is
a. 83.21
b. 84.32
c. 85.57
d. 81.93
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
The interval width is t(df=40,0.95)*7.9/sqrt(41); t-value will be 1.684
interval is 1.684*7.9/sqrt (41)=2.078
The CI is (49.67,53.83)
None of the choices is a confidence interval; they are only single numbers, and none can be either part of the interval.