Use the Given Degree of Confidence and Sample Data to Construct

Multiple Choice

Use the given degree of confidence and sample data to construct a confidence interval for the population mean µ. Assume that the population has a normal distribution.
-The mean replacement time for a random sample of 20 washing machines is 10.2 years and the standard deviation is 2.6 years. Construct a 99% confidence interval for the standard deviation, ?, of the replacement times of all washing machines of this type.

A) $1.8 \mathrm { yr } < \sigma < 4.9 \mathrm { yr }$
B) $1.8 \mathrm { yr } < \sigma < 5.5 \mathrm { yr }$
C) $1.8 \mathrm { yr } < \sigma < 4.3 \mathrm { yr }$
D) $1.9 \mathrm { yr } < \sigma < 4.1 \mathrm { yr }$