You work for a soft-drink company in the quality control division. You are interested in the standard deviation of one of your production lines as a measure of consistency. The product is intended to...

 You work for a soft-drink company in the quality control division.  You are interested in the standard deviation of one of your production lines as a measure of consistency. The product is intended to have a mean of 12 ounces, and your team would like the standard deviation to be as low as possible.  You gather a random sample of 15 containers.  Estimate the population standard deviation at a 90% level of confidence.

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Note: Keep as many decimals as  possible while making these calculations. If possible, keep all answers exact by storing answers as variables on your calculator or computer.

a)  Find the sample standard deviation:

b)  Find the lower and upper χ2χ2  critical values at 90% confidence:
Lower:     Upper:

c)  Report your confidence interval for σσ:  (  ,  )