Compute a 98% confidence interval for the population variance when the sample variance is 20 for a sample of 10 items from a normal population.
A)8.308 to 86.207
B)7.476 to 77.512
C)8.617 to 78.125
D)7.755 to 70.313

Question

Quizplus · Accepted Answer

To compute a 98% confidence interval for the population variance, we use the chi-square distribution. With a sample size of 10, the degrees of freedom is 9. The critical chi-square values for 98% confidence are approximately 2.088 and 21.666. The interval is calculated as ( (n-1)s^2 / χ² upper, (n-1)s^2 / χ² lower ), which results in 8.308 to 86.207.

Compute a 98% Confidence Interval for the Population Variance When