And then we can use that to estimate whether we overestimated or not. So first, let's just find the second derivative. So we have the first derivative written up here. Let me just rewrite it, and I'll distribute the negative 1 4th, because it'll be a little bit more straightforward then. So if I write the derivative of h with respect to time is equal to negative 1 4th times our internal temperature, which itself is a function of time, and then negative 1 4th times negative 27, that would be plus 27 over four. Let me scroll down a little bit. So now, let me leave that graph up there, because I think that might be useful.