A simple random sample of size n is drawn from a population that is normally distributed. The sample mean, x overbar, is found to be 109, and the sample standard deviation, s, is found to be 10. (a) Construct a 90% confidence interval about mu if the sample size, n, is 28. (b) Construct a 90% confidence interval about mu if the sample size, n, is 21. (c) Construct a 70% confidence interval about mu if the sample size, n, is 28. (d) Could we have computed the confidence intervals in parts (a)-(c) if the population had not been normally distributed?