Question

Use the given confidence level and sample data to find a confidence interval for the population standard deviation . Assume that a simple random sample has been selected from a population that has a normal distribution. Salaries of college who took a course in college

​98% ​confidence n​=81 x^-= ​$65,700​   s=​$17,931

the table of​ Chi-Square critical values.

$ < standard deviation < $

Answer 1

For n - 1 = 80 degrees of freedom, we have from chi square distribution tables here:

Also, we have here:

, Therefore,

Therefore the confidence interval for standard deviation here is computed as:

This is the required 98% confidence interval for population standard deviation here.