The following notes may be used for Population mean sigma know 9 2 Reject HO if X In X Za12 Zal2 n Test Statistic Z x o ol n Left tail Reject H0 when Right tail Reject H0 when Two tail Reject H0 when P value left tail p value P Z z right tail p value P Z Z two tail p value P Z z P Z Z Reject HO when O n Population Proportion 9 4 p Za12 Reject HO if Test Statistic P 1 P n 3 Z p Za12 P 1 P n p P 1 P TP