(6.4).7

As part of a water quality survey, you test the water hardness in several randomly selected streams. The results are shown below. Construct a confidence interval for the population variance

2

and the population standard deviation

.

Use a

95%

level of confidence. Assume that the population has a normal distribution.

n=20

s=18

grains per gallon

Question content area bottom

Part 1

What is the confidence interval for the population variance

2?

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(Round to one decimal place as needed.)