A random sample of 30 observations is selected from a normally distributed population. The sample variance is 12. In the 90% confidence interval for the population variance, the upper limit will be:
A) 15.176.
B) 8.177.
C) 19.652.
D) 16.941.

Question

Quizplus · Accepted Answer

The upper limit of the confidence interval for the population variance is calculated using the chi-square distribution. For a 90% confidence interval with 29 degrees of freedom (n-1), the chi-square value for the upper limit is used. The formula is: (n-1)s^2/χ²(α/2), where s^2 is the sample variance. Plugging in the values gives the upper limit as approximately 19.652.

A Random Sample of 30 Observations Is Selected from a Normally