Confidence interval for variance

WlND

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Dec 12, 2011
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A researcher surveys 25 people and finds that their average commute is 15 minutes with a standard deviation of 1.5 minutes. Calculate the 95 percent confidence interval on variance. Do most people have a commute of 20 minutes?

Confidence interval for variance? How is that different from normal variances? should I just use the variance instead of the standard deviation? so 1.5^2=2.25

root 25= 5

\(\displaystyle 15+1.96\frac{2.25}{5} \) and \(\displaystyle 15-1.96\frac{2.25}{5} \)
\(\displaystyle 15+0.882 \) and \(\displaystyle 15-0.882 \)

\(\displaystyle 15.88, 14.12 \)

so, no , most people will not have a commute of 20 minutes

Is this right?

Thanks!
 
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