A random sample of 16 students showed what the variance in the number of hours they spend studying for a final exam was 25 hours^2.
a. Construct a 95% confidence interval for the population variance and standard deviation of hours spent studying. Assume the population of hours spent studying is normally distributed.
b. Test, at the 5% level of significance, whether the population standard deviation of hours spent studying is less than 10. Use the Critical value approach