Speaker 1:	The little zone. Look at this problem. Thirty products per hour come in. We have two types of products, standard products and customized products. You may assume that these products are built in two stations, two plants, two countries. No matter what the practical instantiation is, the process will remain the same. Thirty products per hour come in, they go to the first waiting line. On average, eight products, eight flow units are waiting. Then they go through the first process. Eighty percent of products or flow units go out from there, and the remaining 20% go to the second line when there are an average five flow units waiting. The second process takes 25 minutes, 25 hours, whatever you like to decide. No matter what time unit it is, as long as they are consistent, they work very well. The flow units per hour come in, but in the time period as long as we are consistent in time period. Hundred percent of them go through first waiting line and first process, but only 20% of them go through the second waiting line and second process. We want to compute the flow time of standard products and flow time of the customized products, and flow time of a combination of these two; an aggregate product. If we multiply these percentages by this total incoming, we will get these numbers. 100%*30 is 30, 100%*30 is 30, 20%*30 is six. Therefore, 30 comes here, 30 here, and then 6-30, which is 24 will go out, and six will come here and six will come here and six here. What comes in is 30, and what goes out is 24 from here and six from here, it is still 30. The system that we are talking about is unstable system. Input is equal to output is equal to throughput. Thirty per hour throughput per minute, just divide them by 60, and these are throughputs per minute. There are eight flow units in the first waiting line and five flow units in the second waiting line. We can compute how many flow units are here and how many flow units are here easily. We have this eight here, we have this 12 here, we have this five here, and we have this 25. I have throughput, I have inventory, I can compute flow time because flow time is equal to inventory divided by throughput, and that is 8/0.5, which makes it 16. Here I don't have inventory, but I have flow time and I have throughput. Again, throughput times flow time is equal to inventory. Throughput is 0.1, flow time is 25, therefore, inventory is 2.5. Now, in all pieces of this system, we do have both inventory and flow time. Standard will take 16 minutes over there plus 12 here, and that is 28. Customized takes 28 which is over there, and then we need to add 50, and then we need to add 25. That would be equal to 103. We have 28 and we have 103 over there. We know that 80% follow this pass and 20% follow this pass. If we want to know on average how long it takes a prototype flow unit to pass through this system, open, 28, 80%, 103, 20%, I come here and I type equal to some product of these two numbers and these two numbers. That is the average of them, and I get 43. On average, it takes 43 minutes to pass this system for a prototype product. But there is a different way to do the same thing. If you look at here, the total inventory inside this system, 14, 19, 21.5. That is the total inventory inside this system. Throughput is 30 per hour. Therefore, throughput times flow time is equal to inventory. Thirty times flow time is equal to 21.5. This says the summation of inventory, which was 21.5. This is average inventory. Throughput equal to 30. You have this. Flow time T is equal to inventory divided by throughput. This is 0.71, but this is 43. No problem. This is in hour, this is in minute. It's fine. Divide this one by 60, I get this. If I multiply this by 60, I will get the same thing. As long as we are consistent in using units, we get the same results. Thank you very much for your attention.