Lesson video

Hello everyone, It's Mr. Millar here.

In this lesson, we're going to be interpreting bar charts.

So first of all, hope that you're all doing well and welcome to the final lesson of this unit where we're going to be looking at bar charts and just a reminder that this is the data cycle here.

We're still looking at step 3, where we are representing the data.

We've had looked so far over the last few lessons, at frequency tables, which are a really useful way of representing the data.

But we're going to see in this lesson, that bar charts make the data really, really clear as well.

So without further adieu, let's have a look at the Try this task.

So Jonah counted the number of people in each car passing his school over a one hour period.

He puts his results in a bar chart.

Complete the frequency table and state the mode and range.

So what we can do is we can see that this bar chart is a really nice way of representing the data.

We can see very clearly for example, that we have the number of people in a car down on the x-axis.

And this bar here, two people in a car is the highest bar, it's got the higher frequency, so that is the most common.

So it's a really nice way of seeing the data.

And it's also really important that we know how to put the bar chart into a frequency table.

So there is the frequency table.

We will start off with the first bar, with one person in each car, and we can read up to the frequency and see that there are 12 people or 12 times that there's one person in a car.

So pause the video to copy and complete the frequency table and see if you can find the mode and the range as well.

Great, so going through this, we can just complete one, two, three, four, five here, and then we can simply read off the bar chart to find the remaining frequencies.

So 14 people, or there are 14 times where there's two people in a car.

And then for three, we can see that this lies halfway between the six and the eight.

So that's going to be seven.

Well, the four, that is going to be a frequency of five and finally, a frequency of two here.

So that is the frequency table completed.

It should be nice and straightforward.

And we can see both from the frequency table where 14 is the biggest results.

So therefore the mode is equal to two.

We can also see that, as I said before, from the bar chart, where two is the highest bar and the range, we can also see that the highest piece of data is five.

Subtract the lowest, which is one and we get a range of four.

So nice and straightforward, putting the bar chart into the frequency table and finding the mode and the range.

Let's have a look at the Connect task next.

So here is the Connect task.

Find the mean and median from the bar chart.

So again, we've got the same bar chart as we saw before.

And on the last slide, when we had a look at the mode and the range, it was actually pretty straightforward to work those out just from the bar chart.

But it's not so easy to find the mean and the median just from looking at the bar chart.

So in order to do that, we need to first put the data into a frequency table.

We've done this already.

Here is the frequency table.

So what I want you to do now is to copy down the table, complete this third column here to find the mean.

It should be a nice bit of recap for you about how to find the mean and also see if you can find the median as well.

Pause the video now for three or four minutes.

See if you can work out the mean and the median.

Okay, great.

So I hope that you all did a one times by 12, which is 12.

Two times by 14, which is 28.

Three times by seven, 21.

Four times by five, 20.

Five times by two, just 10.

If we add all of these numbers up, we get 91.

And if we add up all the frequencies, we get 40.

So how do we find the mean? Well, we do 91 divided by 40 and that turns out to the 2.

275.

And remember what I told you a couple of lessons ago.

Whenever we get our answer, we always just make sure, "Does this look sensible?" And yes, it does look sensible.

2.

275 is kind of in-between these numbers here.

So it seems to make sense.

So this is the mean.

How about the median then? Well, there are 40 pieces of data.

So I'm looking at between the 20th and the 21st.

And I can clearly see that it's going to be in this category here because we've got 26 pieces of data within the first two categories.

So it's definitely going to be in that second category here.

The median is two.

Great, hope that was a nice recap of how to find the mean and the median from a frequency table.

It's really important that when you see a bar chart, you're putting it into a frequency table first to help you out.

Great.

Let's now move on to the independent task.

Okay, so here's the independent task.

Find the mean, range, mode and median from this bar chart.

We've got a different bar chart now.

We're looking at number of children per household and number of households.

So what you're going to need to do is pause the video to, first of all, put this data into a frequency table.

So you're going to have two columns, number of children per household, and number of households.

So put the data into a frequency table and then find the mean, range, mode and median.

Pause the video for five or six minutes for this independent task.

Okay, great.

So I hope that you found this nice and straightforward.

First of all, here is the frequency table, which I have completed the third column to help you find the mean and the numbers in the third column sum to 89.

There's 30 pieces of data.

So you're going to have to do 89 divided by 30 to get the mean of 2.

97.

How about the other ones? Well, the mode is nice and straightforward.

You can clearly see that the mode is equal to three.

The range again, nice and easy.

The biggest piece of data minus the smallest piece of data is going to be six.

The mean we've already worked out and the median, well, there's 30 pieces of data.

So I'm looking around the 15th and 16th piece of data.

And well, it's not going to be in the first two here because there's only 11 pieces of data in the first two, but it is definitely going to be in that third one there because 11 plus 11 is now 22.

So the 15th, 16th piece of data is definitely going to be in that category there.

So that is that.

I hope that you found that nice and straightforward.

Let's have a look at the final Explore task now for this unit.

Okay.

Great.

So here we've got another bar chart.

The bar chart below shows the number of bottles of water drunk by members of a swimming team per day.

However, the scale and the frequency axis is missing.

If you know that one of the frequencies is 12, what could the others be? So for example, Anthony is saying, "If four bottles has a frequency of 12, I would know that two bottles would have a frequency of.

." Okay, so what that's saying is, if four bottles had a frequency of 12, then I would know that two bottles, well, I first of all, need to work out the scale and the axis.

So if I'm going up two, to get 12, then what would the first one be? Well clearly that's going to be six.

It's going to go up in sixes.

So it's going to be zero, six, 12, and then you can work out what that is going to be for two bottles.

What if it wasn't four bottles that have a frequency of 12? What if it was two bottles? Pause the video now to explore this task, to see how many different combinations you can find.

Okay, great.

So you should have found that two bottles, if we keep on going up by six each time, we're going to get 24 bottles for two, and we could keep on going up 30, 36.

So you can see that one bottle had a frequency of 36 and so on.

However, if we changed it so that it wasn't four bottles that had a frequency of 12, but instead, let's say two bottles, then the numbers would be different because this time I'm going up one, two, three, four steps.

So each step is going to have to be three.

Zero, three, six, nine, 12.

And therefore we can see that four bottles has a frequency of six and one bottle, if we kept on going would have a frequency of 80.

And so on, we could do exactly the same thing for the other frequencies as well.

So what this Explore task has hopefully shown you is that it's really important that we check out or we know what the scale on the axis is because that will affect all the other values.

So it's really important that we have a good idea of what that is.

Okay, great.

That is it for this lesson and this unit.

Really hope that you've enjoyed this unit.

Thank you for watching all the lessons and well done for doing such great work.

And if you want to share any of your work from this unit, please ask your parent or carer for permission first, and then on Twitter, you can use the @OakNational or the #LearnwithOak to share your work.

Would be really nice to see some of your work.

Fantastic.

Thank you so much for watching all of this and have a great day.

Take care and see you next time.

Maybe in another video or another unit.

Thanks very much.

Bye bye.