Question

Use the birth weights from the data set, “Births,” to construct a 95% confidence interval estimate of the standard deviation of the population from which the sample was obtained.

One sample variance confidence interval:

σ² : Variance of variable

95% confidence interval results:

Variable	Sample Var.	DF	L. Limit	U. Limit
BIRTH WEIGHT	480848.12	399	420524.36	555224.34

After entering this information in StatCrunch Im not sure how to get the Standard deviation

PLEASE POST CLEAR AND LEGIBLE ANSWERS

Answer 1

The standard deviation is the square root of the variance therefore you just need to take the square root of L. Limit and U. Limit to get the 95% confidence interval for standard deviation.

Hence,

Sqrt(420524.36) = 648.48

Sqrt(555224.34) = 745.13

Thus, the 95% confidence interval estimate of the standard deviation of the population from which the sample was obtained is (648.48, 745.13).

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