### Warm-up:

Calculating the Mean

(care of thirdspacelearning.com)

### The Problem:

A rugby team has a mean score of 10.5 after eight games. The next game increases the mean to eleven.

What was the score in that game?

-/|\-

### Solution:

So, we are told that after eight games the mean is 10.5, i.e.,

$$10.5=\frac{S}{8}$$where $S$ is the sum of all the scores and is

$$S=84$$The ninth game adds an unknown amount to this, $84+x$, therefore the new mean

$$11=\frac{84+x}{9}$$So, $x=15$ the score of the ninth game.

### Further Reading:

Averages

(care of revisionmaths.com)

Measures of location and spread

(care of mathswithdavid.com)