At the end of 2008, the variance in the semiannual yields of overseas government bonds was 0.70. A
group of bond investors met at that time to discuss future trends in overseas bond yields. Some
expected the variability in overseas bond yields to increase, while others took the opposite view. A
random sample of 12 overseas bonds taken in March, 2017, generated an average semiannual yield of
3.357 percent with standard deviation 0.8306.
We want to test if the variance in overseas bond yields has changed since 2008. Use significance level
0.05.
1) What are the null and alternative hypotheses?
2) What is the value of the test statistic?
3) What is the rejection region?
4) Do we reject the null hypothesis?
5) Based on this hypothesis test, has the variance in overseas bond yields changed since 2008?
6) Should the p-value for this test be greater than or less than the significance level?
7) Construct a 95% confidence interval for the variance of these bond yields in March 2017.
8) Construct a 95% confidence interval for the standard deviation of these bond yields in March
2017.