1. For sample mean x = 150, sample size n = 36 and sample standard deviation s = 40 find 80% confidence interval for population mean. Population standard deviation is not known, you should use formula on page 328 with t-value fromAppendix Table IV (use column t_0.10).

   135.6 to 148.4

   154.2 to 175.8

   141.3 to 158.7

   162.3 to 187.5