How_To_Be_Good_At_Math

278 STATISTICS •^ THE MEDIAN

Add one giraffe

What happens if another

giraffe, with a height of

4.2 m, joins the group to

make six giraffes? With

an even number of

giraffes, there’s no one

middle height. We can

still find the median by

working out the mean of

the middle two heights.

The median

The median is simply the middle value in a set of data

when all the values are arranged in order, from

smallest to largest or from largest to smallest.

Write down the

heights in order,

starting with the shortest:

2.8, 2.8, 3.7, 3.8, 4.4

Take another look at our

group of giraffes. This

time, let’s work out the

median height.

Now find the middle

height. This is 3.7,

because there are two

heights that are shorter

and two that are taller.

So, the median

height is 3.7 m.

First, let’s arrange

the heights of our

six giraffes in order:

2.8, 2.8, 3.7, 3.8, 4.2, 4.4

Adding one

more giraffe has

changed the median

height to 3.75 m.

The two middle heights

are 3.7 and 3.8. Now

let’s work out their mean:

(3.7 + 3.8) ÷ 2 = 3.75

3.7 m 3.8 m

2.8 m

4.4 m

2.8 m

Extra giraffe

4.2 m

0

4 m

3 m

5 m

2 m

HEIGHT

3.8 m

3.7 m

4.4 m

2.8 m

MEDIAN

2.8 m

1 m

The median is the middle

value when all the values

are arranged in order.

278_279_Median_mode.indd 278 29/02/2016 18:06