Assume there is a sample of n, =4, with the sample mean X, = 45 and a sample standard deviation of S, = 5, and there is an independent sample of n2 = 9 from another population with a sample mean of X2 = 40 and a sample standard deviation S2 = 7. In performing the pooled-variance t test, how many degrees of freedom are there? . . . There are degrees of freedom. (Simplify your answer.)