 Hi, this is Dr. Don. This is part four of the Monte Carlo simulation problem, and I wanted to call something to your attention that I'm saying a lot of folks miss in their assignments that they submitted. In the second part of the assignment, we not only have demand that is varying randomly. We have the unit variable cost in house and the outsource unit cost. Both of those are varying. They need to vary randomly. I'm going to scroll down here. They are done using the lookup method that you can find in the Excel's fun video. What you're doing there, you're taking the discrete frequency distribution that you were given and then converting it into a lookup table, randomizing a variable that will jump up here and select one of these unit prices and report that out. You can see here is reporting out $125. For the unit variable cost for fast, it's done the same way. It's another lookup table. Here, the lookup value is $150. The random variable came here, exceeded $7, dropped back and got $150. Those are linked back into the model. You can see there is the unit variable cost, $150, and the OUC, the outsource unit cost. Those cells, and I'm going to go ahead and make those yellow so we'll know, those cells as well as the demand, all of those are random variables now in our model and we need to include them. You might think that if we just added them into the model and then did our data table the same way of just including the demand random variable and getting our answer for the difference in the decision, that that would give us the same thing as if we included those two new random variables, but it doesn't. And the reason for that is although the top line looks the same, down the column you'll see that the values reported back when you run the simulation are different here. If I don't have them included versus over here where I do, you can see the pattern changes dramatically. I'm going to go ahead and recalculate here a couple of times. You can see that patterns reported back are different because this one does not include those random variables so therefore they're not being keyed to randomize in this data table. Remember data tables link back to cells that you want to change and we want to change these unit variable cells using the random function. If you don't include them in the data table then they don't get updated and the only thing that's getting changed is the demand and the difference and that's the reason that the two columns look so different. So be aware of that when you're adding in additional random variables you've got to put them into your data table to make sure that you're getting the the correct simulation. You're not just getting a partial simulation. I hope this helps.