A simple random sample of size n is drawn from a population that is known to be normally distributed. The sample variance, s squared, is determined to be 13.4. Complete parts (a) through(c). (a) Construct a 90% confidence interval for sigma squared if the sample size, n, is 20. The lower bound is nothing. (Round to two decimal places as needed.) The upper bound is nothing. (Round to two decimal places as needed.)
(b) Construct a 90% confidence interval for sigma squared if the sample size, n, is 30. The lower bound is nothing. (Round to two decimal places as needed.) The upper bound is nothing. (Round to two decimal places as needed.) How does increasing the sample size affect the width of theinterval? The width increases The width does not change The width decreases
(c) Construct a 98% confidence interval for sigma squared if the sample size, n, is 20. The lower bound is nothing.(Round to two decimal places as needed.) The upper bound is nothing. (Round to two decimal places as needed.) Compare the results with those obtained in part (a)
How does increasing the level of confidence affect the confidence interval? The width increases The width decreases The width does not change