This content was created by Rob Langman. This content was uploaded by Rob Langman. This is a YouTube video titled "Using Bar Models To Solve Ratio Problems" (created 2024-04-03) containing an English instructional math tutorial. The lesson is presented by Ellie (labelled SPEAKER A) with interjections from a second speaker (SPEAKER B). They demonstrate using bar models to solve a ratio word problem about baking (butter to flour 4:9), showing how 30 g of butter leads to 67.5 g of flour. The content is aimed at pupils or teachers as a classroom-style explanation.
Questions this video answers
4:9
30 grams
67.5 grams
Chapters
Hi, I'm Ellie, and in this video we're going to look at how we can use bar models to help us solve word problems involving ratios. So in this example we're looking at a ratio involved in baking, which is a common example that you might use with your class. Mr. Matthews was baking some cookies.
He combined butter and flour in a.
4 to 9 ratio. He used 30 grams of butter, half.
How much flour did he use. So what we want to start with.
Is by representing the amount of butter he used, because we know that that was 30 grams. So for this I'm going to draw.
A bar.
And we're going to label.
This to show that this is 30 grams.
And the ratio is four to nine.
So I want to divide this into four equal parts, because for every four.
Parts of butter he used, our ratio means that he used nine parts of flour.
These are equal parts.
So we need nine equal sized parts.
To represent the flour. So there's the four.
And we need.
Five more parts the same size.
I'm just going to add them on like this to help me make sure.
It'S roughly the right size. Okay, so I've got four parts butter, nine parts flour. The question had asked us how much flour he used. Now, you want your pupils to be able to tell you that because these parts are all equal, we can find.
Out one of them quite simply with the amount of butter that we have.
By dividing 30 by 4. So if we do 30 divided by.
4, pupils can choose whatever method they want to use. They might decide to do that quickly in their head.
30 divided by 2 is 15, half.
Of that is 7.5.
So each of these boxes is 7.5 grams of butter. So then we can see that we're.
Starting to get nearer to finding the answer of how much flour we want.
To find out this amount here, this is our unknown.
But now we do know something. We know that this is 7.5.
So then it's really a simple step.
Of the pupil seeing that all they need to do is multiply 7.5 grams by nine, because it's nine equal parts and they'll be able to find the answer. So 7.5 times by 9, which will give us 67.5 grams. And that's your answer to the question. Mr. Matthews used 67.5 grams of flour, and that's how we can use bar modelling to help solve ratio problems.
