Lesson video

Hi, I'm Miss Davies in this lesson, we're going to be looking at stem and leaf diagrams. This stem and leaf diagram shows the length of some worms in centimetres.

We have been given a key in which in explains that three line one means 3.

1 centimetres.

All of the numbers that are on the left of this line are the stems. These in this question, are in our ones column.

The numbers to the right of the line are the leaves in this question they're in the tenths column.

We have been asked how many worms are measured.

To answer this question, we need to count the number of digits on the right of the line.

This is 17.

The length of the largest worm is 5.

4 centimetres.

This is the furthest bottom-right of our stem and leaf diagram.

Stem and leaf diagrams should always be in ascending order.

The range of the length is found by finding the difference between the largest value and the smallest value.

The largest value is 5.

4, smallest value is 2.

1 To calculate the range, we're going to do 5.

4 subtract 2.

1 which gives an answer of 3.

3 centimetres.

This next stem and leaf diagram shows the time taken for some runners to complete a 400 metre run.

This time, we've got two digits on the left hand side of the line.

We've been told from the key that four three line one represents 43.

1 seconds.

We've been asked how many runners finished the race in under 45 seconds.

This means that we're looking at the number of digits on the right hand side of the line in the first two rows as these are below 45.

This is seven.

The modal time is the time that appears the most.

This is 45.

5 seconds as it appears three times.

The median time is the time that is in the middle in our set of data.

This is halfway between 45.

2 and 45.

5 The middle number of these two is 45.

35 seconds.

Here is some questions for you to try, pause the video to complete your task and resume once you're finished.

Here are the answers.

The stem numbers in this question are the ones and the leaf numbers are the tenths.

Here is some questions for you to try, pause the video to complete your task and resume once you're finished.

Here are the answers.

The stem numbers in this question are tenths and the leaf numbers are ones.

The numbers in your stem and leaf diagrams should be in ascending order.

There should also be a key you could have used any number from the diagram in your key.

This is a back to back stem and leaf diagram.

It is used to compare two sets of data.

Were going to calculate the range of the number of eggs laid on Farm A.

To calculate the range of a set of data we're going to find the difference between the largest value and the smallest value.

The largest value in this set of data is 48 the smallest value is one.

To calculate the range we're going to do 48 subtract one which gives an answer of 47.

Now we're going to have a look at Median.

We're going to find the middle number in each set of data.

For Farm A this is 22.

5 for Farm B it is 22.

This means that Farm A have the highest median.

Here is some questions for you to try, pause the video to complete your task and resume once you're finished.

Here are the answers.

The median age of Choir A is 42.

5 and in Choir B it is 50.

The range of the ages in Choir A is 49 and in B it is 53.

Here is some questions for you to try, pause the video to complete your task and resume once you're finished.

Here are the answers.

The median would change, the mean will increase as 23 Pounds is higher than the original mean.

The range will stay the same because 23 Pounds isn't the smallest or the largest fare.

That's all for this lesson, thanks for watching.