Lesson video

Hello, my name is Mr. Clasper and today we are going to be drawing and interpreting a frequency tree.

In this lesson we're going to draw and interpret a frequency tree.

A frequency tree helps us categorise different frequencies.

In this question, we're told that 50 people were asked if they wore glasses.

27 of these were men, 14 of the women wore glasses, and 15 people asked did not wear glasses, and we need to complete the frequency tree.

Well, the first piece of information we can input is that there are 50 people altogether.

So the overall frequency, goes in the first section to the left of our diagram.

Now we know this, we can move ahead with the other details from the question.

So we're told that there were 27 men.

So we can put 27 in the category, which says men.

In the next section, it says 14 of the women wore glasses.

So within the women category, we need to make sure that we have 14 of these who wear glasses.

This would go in this section of the diagram.

The last part says 15 people asked, did not wear glasses.

We can't tackle this piece of information just yet.

As we don't know how many men didn't wear glasses and how many women didn't wear glasses.

We only know that 15 people altogether did not wear glasses.

So let's have a look at this in more detail.

Using the information we have so far, we should be able to find some other details.

So for example, if we know there are 50 people all together, and 27 of these are men, this must mean that there are 23 women.

So our total of 50, subtract 27 leaves us with 23.

So in our diagram, we can now put 23 women.

And we can check this because the sum of 23 and 27 is 50.

We can also find out how many women don't wear glasses, as we now know the total number of women which is 23.

And we know that 14 of these were glasses.

This must mean, that nine women don't wear glasses as 23 subtract 14 gave us nine.

And again, we can check this as the sum of 14 and nine is 23.

The next part of the question, we're going to focus on this piece of information, we were told 15 people who were asked, did not wear glasses.

Now we know that there are nine women who didn't wear glasses.

This is a piece of information we know now.

And we can use this, to help us find out how many men don't wear glasses.

So if there are 15 people altogether, who do not wear glasses, and nine of these are women, then this must mean that there are six men who don't wear glasses.

And for the last piece of information, we know the total number of men is 27.

And we now know that six of these don't wear glasses.

Therefore, there must be 21 men who wear glasses as we take the total which is 27 and subtract six who don't wear glasses and this leaves us with our 21, we've now completed our frequency tree.

Here is a question for you to try.

Pause the video to complete your task and click resume once you're finished.

And here are your solutions.

So we had 20, boys and girls all together.

So this was our first section to complete.

If we know there are 12 boys, that must mean that there are eight girls as we have 20 of these all together, and out of 12 boys if seven like football then this means that five do not and out of our eight girls, if two don't like football, then this means that six of them must like football.

And here's another question for you to try.

Pause the video to complete your task and click resume once you're finished.

And here are your solutions, so we have 40 people all together in the diagram.

If 12 don't like tea, then this means that 28 of the most like tea.

If we skip further ahead in the question, we find out that six people didn't like tea or coffee.

So this means out of our 12 people who don't like tea, six of these must also not like coffee.

So this means I have six people who don't like tea out of the 12 who don't like tea.

And this means that there must be six people, who like coffee out of the people who don't like tea.

And now that we know this, if there are six people who don't like tea, and like coffee, this must mean that there are 12 people who like tea and like coffee, as there were 18 of these altogether.

And here is your last question.

Pause the video to complete your task and click resume once you're finished.

And here is your solution.

So if we look at our frequency tree, we can see that there are 17 girls who like school, and there are seven boys who likes school.

But the question asked us how many more girls like school than boys? So we need to find the difference between the two frequencies.

So 17 take away seven give us 10.

So there are 10 more girls who like school more than boys.

And this is the end of our lesson on frequency trees.

Why don't get the exit quiz go to show off your skills.

I'll hopefully see you soon.