What formula do I use for this problem

Ho: u = -2 X=-2.17 standard error of x = 0.81 (round your answers to 2 decimal place) The approximate 95% CI for u is to The result of the hypothesis test is: O Reject Ho, because the null value is inside the 95% CI. O Reject Ho, because the null value is outside the 95% CI. O Fail to reject Ho, because the null value is inside the 95% CI. O Fail to reject Ho, because the null value is outside the 95% CI