 In this video, we provide the solution to question number six for practice exam number two for Math 1030, for which a project digraph is illustrated right here, and we're asked to compute the critical time for the project. So we're going to go through and calculate the critical times of each of these things starting at the end. We're going to backflow here. So the end costs nothing. This one's going to cost six. This one will cost four. This one will cost seven. Like so. So then going on here, this one would cost ten, three plus seven. This one, D, has a lot of successors. You've got six, four, and seven. Seven's the most expensive one. So you're going to take five plus seven, which is twelve, like so. A is only followed by F, so you're going to get three plus six, which is nine. B is followed only by D, so you're going to take seven plus twelve, which is nineteen. C is likewise. It's followed by D, but it's also followed by E. E has a critical time of ten. D has a critical time of twelve. So that one, you're going to get twelve plus fourteen, excuse me, twelve plus two, which is fourteen. And so then comparing these, you have nine, you have nineteen, and then you have fourteen. The largest one is going to be nineteen. So that is going to be the critical time of the entire project. So we see that the correct answer is E. The critical time is nineteen.