A random sample size n is drawn from population that is known to be normally distributed. The sample mean, x, is estimated to be 54.8.
A. Develop the 90% confidence interval for population mean if the population standard deviation, s, is known to be 10.5 and sample size, n, is 20.
B. Develop the 90% confidence interval for the population mean if the population standard deviation, s, is known to be 10.5 and the sample size, n, is 30. How does increasing the sample size affect the width of the interval?
C. Develop the 99% confidence interval for the population mean if the population standard deviation, s, is known to be 10.5 and the sample size, n, is 20. How does increasing the level of confidence affect the confidence interval?