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A study of annual growth of cacti indicated $64$ of them, selected at random, had a mean annual growth of $52.80$ mm with a standard deviation of $4.5$ mm. Construct a $99$% confidence interval for the standard deviation of the annual growth.

My book has nothing on estimating standard deviation. I know variance uses the chi square table so I thought if I took the square root of the variance, I could get standard deviation. However, the table in the back of my book does not go to $64$. :(

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Research Central Limit Theorem

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Please add a bit more detail, and perhaps some starting points. – vonbrand Mar 25 '13 at 4:20
Start by reading the Wikipedia article on the CLT. It is directly applicable to your problem. – Dale M Mar 25 '13 at 5:07

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