Using Bar Models To Solve Complex Problems (Additive & Multiplicative)

Hi, my name's Ben. In this video we're going to be looking at the bar model in solving word problems, complex word problems that involve all four operations. It's worth noting that this sort of question may fetch up to 3 marks on one of the year 6 SATS papers. Let's look at the question. Three children swam a total of 2.7 kilometres in a sponsored swim. Rob swam half the distance of Diana. George swam 130 meters less than Diana. How far did each child swim? Okay, Diana is key in this problem. So let's make sure that we really focus on Diana. Okay? We don't know how much she swam at the moment, so we're putting her down as an unknown. We do know that it said that Rob swam half the distance of Diana, and therefore Diana swam twice the distance of Rob. So Rob's bar is half the size. We then look at George. Now it says that George swam 130 metres less than Diana. So we have a difference of 130 meters. All this combined gives us 2.7 kilometers or 2,700 meters. Again, it's worth noting here that we're dealing with meters and kilometres. The children have to know be able to convert between meters and kilometers. And if that's something you need to practice, I advise you do before you tackle this sort of problem. Now, in order to make this problem solvable, we need to adjust one of the bars. We are going to add 130 meters onto George's Bar because now that makes five times the amount of Rob's. So now Our total is 2,830 meters. We can take that total of 2,830 meters and divide it by five. Because we have now 5 parts and 2830 divided by 5 is 566 meters. Again, the children will probably use a short division method to solve that one. So now we know that Rob's distance is 566 meters. If Rob's part is worth 566, each of Diana's parts will also be worth 566 meters, which means that her total is 1,132 meters. George's two parts, which would also be 1132 meters. We have to subtract the 100 and 30 that we added before. So 1132 subtract 130 equals 1002 meters. So now we have each of their distances. George swam 1002 meters, Diana swam 1132 meters and Rob swam 566 meters. What a final step here for the children would be is to add those totals together to see if they get 2,700 meters, which they should do. And that's how you can use the bar model to solve a really complex multi step word problem.