Use the Given Degree of Confidence and Sample Data to Find

question 156

Multiple Choice

Use the given degree of confidence and sample data to find a confidence interval for the population standard deviation σ.
Assume that the population has a normal distribution. Round the confidence interval limits to the same number of decimal places as the sample standard deviation.
-The mean replacement time for a random sample of 20 washing machines is 10.9 years and the standard deviation is 2.7 years. Construct a 99% confidence interval for the standard deviation, σ, of the replacement Times of all washing machines of this type.

• A) \(1.9 \mathrm { yr } < \sigma < 5.7 \mathrm { yr }\)
• B) \(1.8 \mathrm { yr } < \sigma < 5.1 \mathrm { yr }\)
• C) \(2.0 \mathrm { yr } < \sigma < 4.3 \mathrm { yr }\)
• D) \(1.9 \mathrm { yr } < \sigma < 4.5 \mathrm { yr }\)

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Definitions:

Sierra Legal Defence Fund

An organization dedicated to using legal avenues to protect the environment and advocate for conservation efforts, now known as Ecojustice Canada.

Raw Sewage

Untreated, unfiltered waste water and contents from residential, commercial, and industrial sources, containing a variety of contaminants.

Sierra Legal Defence Fund

A Canadian environmental law organization, now known as Ecojustice Canada, that provides legal representation and advice for environmental causes.

Raw Sewage

Untreated, unfiltered wastewater containing contaminants such as human waste, industrial runoff, and debris, requiring treatment before being released into the environment.