Question

The confidence interval below for the population variance is based on the following sample statistics: n = 25, x-bar = 31.1, and s = 4.2.

9.29 < standard deviation squared < 42.82

What is the degree of confidence?

Answer 1

99% is the degree of confidence.

To check:
Use 2.58 to represent 99%. Find the formula for the confidence interval using standard deviation. Remember that standard deviation is the square root of the variance. Substitute what you know into the formula from the information given to check.

Answer 2

I know the formula. How do you work backwards?