Question

The following data represent the pH of rain for a random sample of 12 rain dates in a particular region. A normal probability plot suggests the data could come from a population that is normally distributed. A boxplot indicates there are no outliers. The sample standard deviation is sequals0.313. Construct and interpret a 95​% confidence interval for the standard deviation pH of rainwater in this region. 4.52 5.32 4.98 4.78 4.84 4.75 5.60 4.67 4.93 4.78 4.75 4.53

Answer 1

The statistical software output for this problem is :

One sample variance confidence interval:
σ² : Variance of variable

95% confidence interval results:

Variable	Sample Var.	DF	L. Limit	U. Limit
Data	0.097735606	11	0.049046042	0.2817512

A 95​% confidence interval for the standard deviation a 95​% confidence interval

for the standard deviation is :

(0.22 , 0.53)