Answer to Question #184435 in Statistics and Probability for Monina Saraza

Question

The 95% confidence interval for the variance and standard deviation for the sugar content in an ice cream (in mg) if the sample of nine servings has a variance of 36.

Answer 1

Consider that the sample mean $= 10 = \bar x$

Sample variance $= s = 36$

Sample size = $9$

z score for 95% confidence $= 1.96$

Hence,

$CI = \bar x \pm z \dfrac{s}{\sqrt{n}}$

$CI = 10 \pm 1.96 \times \dfrac {36}{3}$

$CI = 10 \pm 23.52$