Do we know that it's even close? No, we don't know for sure, but that would be the best estimate. It would be better than trying to take the average rate of change between when x equals three and x equals six, or between when x equals zero and x equals nine. These are pretty close around four. And so let's do that. Let's find the average rate of change between when x goes from three to five. So we can see here our change in x, let me do this in a new color.