question 2 (20 percent) Q.2.(Estimation I - Confidence Interval for Population Mean): Consider a random sample of n = 12 from a normally distributed population of large size has ¯ X = 25 and s2 = 8. i. Assume that you know the population has a population variance ?2 = 16. Form a 99% confidence interval for µ. ii. Assume that the population variance is unknown. Form a 99% confidence interval for µ. Now consider a random sample of n = 30 from a population with unknown distribution has ¯ X = 25 and s2 = 8. iii. Assume that you know the population has a population variance ?2 = 16. Form a 99% confidence interval for µ. iv. Assume that the population variance is unknown. Form a 99% confidence interval for µ. service life is exactly 105 years?