Lesson video

Hi, I'm Miss Davis.

In this lesson, we're going to be working out the mean, median, mode and range from a list of numbers.

These are what are generally called the averages.

Which of them are actually averages though? Mode is an average.

Median is an average.

Mean is an average.

And this is what people tend to refer to if they are generally saying an average.

Range is not an average, it is a spread of the data.

Let's match the names to the definitions of the averages.

Mean is the total divided by the number of items. Median is the middle item when they are in order.

Mode is the most frequent item.

And the range is the difference between the largest and smallest values.

Here are some test scores.

We're going to find the mean, median, mode and range of the test scores.

Let's start by calculating the mean.

If we add all of these numbers together, we get 571.

There are nine numbers in this set of data.

So we're going to calculate 571 divided by nine.

This gives us an answer of 63.

4, I've rounded this to one decimal place.

To work out the median, mode and range, we need to put the numbers in order.

This can be in either ascending order or descending order.

To find the median value, we need to find the middle item.

I'm crossing off one number from each side, in turn, until we're left with one in the middle.

The median is 65.

To find the mode, we are looking for the most common number, 65 appears in this list twice.

So 65 is our mode.

The range is found by calculating the difference between the largest and the smallest value.

In this case, 92 and 28.

The range is 64.

We have got another set of numbers.

Let's start off by finding the mean.

The total of these numbers is 632.

If we divide this by eight, it gives us a mean of 79.

To find the median, going to write them in order and cross off one number from each side in turn, until we're left in the middle.

This time we've been left with two numbers in the middle, we need to find the number that is halfway between 75 and 77.

The median is 76.

There isn't a mode with this question as each number appears once.

The range is found by subtracting 63 from 99.

This gives us an answer of 36.

Here are some questions for you to try.

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

Here is the answer.

Amir hasn't ordered the numbers in either ascending order or descending order before finding the range on the median.

To find the range, the calculation that he needed to do was 38.

6 subtract 19.

2.

The correct median is 32.

5 metres.

Here are some questions for you to try.

Pause the video, to complete your task and resume once you're finished, Here are the answers.

To calculate the mean you need to find the sum of the numbers and divide this by the frequency, where the frequency is how many numbers there are.

The mode is the most common number.

In part D, where zero and 0.

5 appear twice in the list.

So they are both the mode value.

Here are four number cards.

The mean of these four number cards is five.

We've been asked to find the value of the missing card.

If we note that the mean of the four cards is five.

This means that the total of the cards must be 20.

As 20 divided by four is five.

Something is found by calculating 20, subtract nine added to six, add three.

So our missing card is two.

Here are some questions for you to try.

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

Here are the answers.

There are 10 different answers for the first part.

As long as your four numbers have a sum of 16, the mean will be four.

Here are some questions for you to try.

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

Here are the answers.

For question five, you could have also replaced six and 11 with three and 14, four and 13, five and 12 or seven and 10.

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