A random sample of 20 students yielded a mean of ¯x = 72 and a variance of s 2 = 16 for scores on a college placement test in mathematics. Assuming the scores to be normally distributed, construct a 98% confidence interval for σ 2 . Be sure to
a. State if the problem involves 1 population or 2 populations. If you have 2 populations, should they be paired or not?
b. State α.
c. State whether you should use z, t, or χ 2 and find / provide the appropriate value(s) from the table (or your calculator).
d. Find the confidence interval. Round your final values to 3 decimals. • Write a verbal interpretation of your confidence interval.
