What Is the 90% Confidence Interval for the Variance of Exam

Multiple Choice

What is the 90% confidence interval for the variance of exam scores for 28 algebra students, if the standard deviation of their last exam was 12.7?

A) $108.6 < \sigma ^ { 2 } < 269.6$
B) $10.4 < \sigma ^ { 2 } < 16.4$
C) $123.7 < \sigma ^ { 2 } < 312.7$
D) $122.8 < \sigma ^ { 2 } < 316.5$