How_To_Be_Good_At_Math

276 STATISTICS •^ AVERAGES

Types of average

We can use three different

types of average to describe a

set of data, such as the heights

of a group of giraffes. They are

called the mean, the median,

and the mode. Each one tells

us something different about

the group. But they all use a

single value to represent the

group as a whole. To find out

more, see pages 277-79.

Averages

An average is a kind of “middle” value used to represent a set

of data. Averages help you to compare different sets of data,

and to make sense of individual values within a data set.

Not typical of team Typical of team Not typical of team

The average age of the Reds football

team is 10. Not all the players are 10

years old – some are 9 and some are 11.

But 10 is the age that is typical of the

team as a whole.

The average age of the Blues

football team is 12. Comparing the

two averages, we can see that the Blues

team is, typically, older than the Reds.

An average can also tell

us if an individual value

is typical of the data set or

unusual. For example, the

Reds’ average age of 10 can

tell us if these three players

aged 9, 10, and 11 are

typical of the team or not.

3.7 m 4.4 m 2.8 m 2.8 m 3.8 m

Average

age = 10

Average

age = 12

MEDIAN

MODE

MEAN

12 12 12 12 12 12

11 12 12 1312

9 10 11

age age age

2.8 m

3.7 m 3.5 m

10 10 10 10 10 10

99 10 11 11

The average is the value

that’s most typical of

a set of data.

Player’s age

276_277_Averages_mean.indd 276 29/02/2016 18:06