Calculate the following: a) Determine the sample size necessary ...

      1.  Calculate the following: a) Determine the sample size   necessary to estimate a population mean to within 1 with a 90% confidence   given that the population standard deviation is 10. b) Suppose that the   sample was calculated at 150. Estimate the population mean with 90%   confidence  

     2. a) From   the information given here, determine the 95% confidence interval estimate of   the population mean. Xbar = 100 s = 20 n = 25 b) Repeat part (a) with xbar =   200. c) Repeat part (a) with xbar = 500 d) Describe what happens to the width   of the confidence interval estimate when the sample mean increases.