Mean

curriculum-key-fact
The mean is the most commonly used measure of average. To calculate the mean, add the values together and divide the total by the number of values.

Example

Question

Five friends compare their marks in a French test. See the table below:

NameMark
Shabana\[{41}\]
Bea\[{54}\]
Liam\[{79}\]
Dave\[{26}\]
Ed\[{65}\]

What is the mean mark?

Mean \(=(41 + 54 + 79 + 26 + 65) \div 5\)

\[= 265 \div 5\]

\[= 53\]

Notice that the mean does not have to be any of the given data values.

curriculum-key-fact
Check your answer by asking yourself if it looks correct. If you had forgotten to divide by 5, then the answer would be 265, which is incorrect.
Question

A die is thrown \(10\) times. These are the results:

\[3,~5,~1,~2,~6,~4,~2,~5,~6,~1\]

What is the mean score?

To find the answer, add the values together and divide the total by the number of values:

Mean \(= (3 + 5 + 1 + 2 + 6 + 4 + 2 + 5 + 6 + 1) \div 10\)

\[35 \div 10 = 3.5\]