Median

This is Johnny. He's with his sister Kate and his brother Matt.

They're arranged from smallest to tallest!

Who's in the **middle**?

Yes, Johnny's in the middle!

In this lesson, we're going to explore an idea that has something to do with middle.

It's called **median.**

In Math, when we hear the word "middle", we think about median.

Medianis the value in themiddleof a set.

**Set **means a group of numbers.

A **value **is what's inside a set. It can be a number, object, or thing.

Look at this set of numbers.

5, 4, 7, 2, 9, 8, 6

Can you figure out the **median **for this set?

To do this, you need to...

**(1)**** Order the numbers **from smallest to largest.

That would be...

2, 4, 5, 6, 7, 8, 9

**(2)**** Count how many **numbers are in the set.

We see that there are 7 numbers.

**(3)**** Find the middle number.**

Which number is in the middle?

That's right - it's the 4th number!

2, 4, 5,6, 7, 8, 9

The median for this set is 6. 😃

😃 **Tip:** You know that **a number is in the middle **when the number of values to the left of it are equal to the number of values to the right of it.

In our example, there are 3 numbers to the left of 6 and 3 numbers to the right of 6.

Find the median for this set.

9, 24, 35, 27, 11, 19, 23, 13, 17, 24, 21

Where do we start?

First, we **order the numbers **from smallest to greatest:

9, 11, 13, 17, 19, 21, 23, 24, 24, 27, 35

Then, we count the numbers.

How many are there?

11!

Which **number **is in the **middle**?

It's the 6th number.

9, 11, 13, 17, 19,21, 23, 24, 24, 27, 35

The median for this set is **21**.

😃 Tip: It doesn't matter that some numbers in the list are the same. You still need to write them in the list.

Let's try this example.

39, 28, 45, 33, 31, 45, 32, 37

👉 We **order the numbers **from smallest to greatest.

We'll have...

28, 31, 32, 33, 37, 39, 45, 45

👉 We **count the numbers.**

There are 8 numbers. That's an even number!

This means that we don't just have 1 middle number, but we have 2!

28, 31, 32,33,37, 39, 45, 45

👉 When we have **2 numbers in the middle,** we have to **find their ****mean,**** or average.**

To find the mean of the 2 middle numbers, **we do 2 steps:**

1. We add them together.

33+37=70

2. Then, we divide the sum by 2.

70÷2=35

The median for this set is **35.**

Did you notice that 35 is not in the list? That's okay!

👉 Our **median **is still 35.

Great job learning about median.

The **median **is the middle number in a set.

Now try the practice problems. 😃

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