They could call this x subscript four, they could call this x subscript five, and so if you had n of these, you would just keep going, x subscript six, x subscript seven, all the way to x subscript n. And so to take the sum of all of these, they would denote it as the sum, let me write it right over here, so they will say that the sample mean is equal to the sum, the sum of all of my x sub i's, my x sub i's, so the way you can conceptualize it, these i's will change, so the i's are going to, in this case, the i started at one, the i's are going to start at one until the size of our actual sample, so all the way until n. In this case, n was equal to five. So this is literally saying, this is literally saying, this is equal to x sub one plus x sub two plus x sub three, all the way, all the way to the nth one. Once again, in this case, we only had five. Now, are we done? Is this what the sample mean is? Well, no, we aren't done. We don't just add up all of the data points.