Relationship Longevity Homosexual Couples Heterosexual Couples X1 = 15.2 years X2 = 16.7 years s1 = 9 years s2 = 12 years N1 = 31 N2 = 30 Use the t distribution table that follows to find the critical t-score, the value for a t-score that separates the tail from the main body of the distribution, forming the critical region. To use the table, you will first need to calculate the degrees of freedom (df). The degrees of freedom are . With = 0.05, the critical t-score is