We can determine the P-Value when the number we supply as the first argument to the TDIST(), at which we must evaluate the distribution, is negative. For example, the below table contains two sets of TDIST() argument values, with x being negative in both sets. Suppose we must compute and show the one- and two-tailed t-distribution probability percentages in cell range D8:D9 for the two specified value sets. And consider the target cells’ data format is Percentage. Then, the TDIST Excel function in the target cells will fetch us the required probability values. • Step 1: First, select the target cell D8, enter the following TDIST(), and then, press Enter. =1-TDIST(2,50,1) • Step 2: Next, select the target cell D9, enter the following TDIST(), and press Enter. =TDIST(2,50,2) In both types of t-distributions, the first argument value in the TDIST() should be positive. However, for the one-tailed t-distribution, we must subtract the TDIST() output from 1 to achieve the required P-Value. On the other hand, for two-tailed t-distribution, we can get the P-Value using the TDIST() formula we would apply when x is positive.