The 99% confidence interval estimate for a population variance when a sample standard deviation of 12 is obtained from a sample of 10 items is
A) 4.589 to 62.253.
B) 46.538 to 422.171.
C) 54.941 to 746.974.
D) 62.042 to 562.895.

Question

Quizplus · Accepted Answer

The formula for calculating a confidence interval for population variance when sample standard deviation is known is:

((n-1)s^2) / chi-square value
where:
n = sample size
s = sample standard deviation
chi-square value = critical value from chi-square distribution table at (1- confidence level) and (n-1) degrees of freedom.

Substituting the given values, we get:
((10-1) * 12^2) / 3.247 = 54.941
((10-1) * 12^2) / 0.064 = 746.974

Therefore, the 99% confidence interval estimate for a population variance is 54.941 to 746.974. 
Hence, the correct choice is C.

The 99% Confidence Interval Estimate for a Population Variance When