Step 3 Expressing 95% as a probability gives 0.95. Thus, we have (1 - a) = 0.95, so a = 0.05. Therefore,_ = 0 025 2 Now that the upper tail area is known, the degrees of freedom need to be found to give the specific value of t. Recall that 64 families in this sample, so n degrees of freedom = n - 1 Enter an exact number. Submit Skip (you cannot come back) Need Help? Read It