Video: Reading Bar Graphs with Nonunit Scales

The bar graph shows the sports that children play after school. How many more children play baseball than football? How many children play hockey or tennis?

05:22

Video Transcript

The bar graph shows the sports that children play after school. How many more children play baseball than football? How many children play hockey or tennis?

In this problem, we’re given a bar graph which shows the sports that children play after school. And we can see that there are four different sports. This orange bar shows the number of children that play football. Then, we have the number of children who play baseball, followed by hockey, and lastly tennis. These different sports are listed across the bottom of the graph, the 𝑥-axis. And the 𝑦-axis is numbered from zero to 100. This must be the number of children.

We can see that the axis is marked in intervals of 10, 10, 20, 30, 40, and so on, all the way through to 100. But we can also see that the graph has been drawn on squared paper. And in between each interval of 10, there are five different squares. This means that each small square on the graph represents two. We have two questions to answer in this problem. And the first asks is how many more children played baseball than football.

And to help us answer the question, we’re given what looks like a zoomed-in part of the graph. It shows us the part that we need to concentrate on. The blue bar here is the top of this blue bar. It shows us the number of children who play baseball. And the top of this orange bar is the bar that shows us the number of children who play football. So, we need to calculate the difference between these two amounts.

Firstly, let’s calculate how many children play football. We can see that the interval that represents 30 is here. But the top of our bar is one, two, three more squares than 30. We said that each small square was worth two. So, let’s count in three more twos, 32, 34, 36. The number of children who play football is 36. Now, let’s read the bar graph to find out the number of children who play baseball. We can see that the interval that represents 70 is here. And the top of the bar graph is two more small squares than that. Let’s count in twos twice, 72, 74. The number of children who play baseball is 74.

So, how many more than 36 is 74? Let’s count on from 36 to help us find the answer. First of all, we can add to get to the next 10. So, if we add four, it takes us to 40. Now, we can do a large jump to the nearest 10 to our target, which is 70. We need to add 30 to 40 to get to 70. And then, finally, a jump of four takes us to 74. So, the difference between 36 and 74 is four plus 30 plus four, which equals 38. 38 more children play baseball than football.

Our final question asks us how many children play hockey or tennis. To find this answer, we need to find the total of the number of children that play hockey and also those that play tennis. This will give us the number of children that play hockey or tennis. We don’t have a zoomed-in part of the graph to look at, so we’re going to have to use the main bar graph to help us.

First of all, let’s find the number of children that play hockey. If we draw the line across level with the top of the bar that represents hockey, we can see that 20 children play hockey after school. The pink bar represents those children that play tennis. And we can see that a line has already been drawn across for us.

The multiple of 10 that the top of this bar is nearest to is 50. But we can see that the top of the bar is two more small squares above 50. So, we need to count in twos two more times, 52, 54. So, to find the number of children that play hockey or tennis, we need to add 54 and 20 together. When we add 20, we’re simply adding two more 10s. So, the answer, the total, is going to be 74.

For each question, we read the graph carefully to find the information that we needed. And then, we used that information to calculate. To find how many more children play baseball than football, we calculated 74 take away 36, or the difference between those two numbers. And the answer is 38. And then, to calculate the number of children that play hockey or tennis, we needed to add together 54 and 20. And the answer to that was 74.

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