In order to estimate the average daily down time, a manufacturer randomly sampled 41days 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)	51.75 4.76
B)	51.75 3.28
C)	51.75 2.08
D)	51.75 1.30
Answer:C
In order to estimate the average daily down time, a manufacturer randomly sampled 41days 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)	51.75 4.76 B)	51.75 3.28 C)	51.75 2.08 D)	51.75 1.30