What formula do i use to figure out this problem

For each question, create an approximate 95% CI and then decide whether the null hypothesis should be rejected. H0: pi = 50 E=ss.4 standard error of E = 2.5 {round your answers to 1 decimal place} The approximate 95% CI for u is :| to :| The result of the hypothesis test is: D Reject Ho: because the null value is inside the 95% CI. 0 Reject HD, because the null value is outside the 95% Cl. C} Fail to reject HD, because the null value is inside the 95% CL. C! Fail to reject HD, because the null value is outside the 95% CI