But if you know n minus 1 of them, you can always figure out the nth one if you know the actual sample mean. So in this case, for any of these groups, if you know 2 of these data points, you can always figure out the third. If you know these 2, you can always figure out the third if you know the sample mean. So in general, let's figure out the degrees of freedom here. You have, for each group, when you did this, you had n minus 1 degrees of freedom. Remember, n is the number of data points you had in each group. So you have n minus 1 degrees of freedom for each of these groups, so it's n minus 1, n minus 1, n minus 1.