Finding the mean

1
Finding the mean

• of a set of numbers

2
A mean

• is one of three types of average.

• The others are the median and the mode.

• The mean is the sum of the values divided by
  the number of values.

3
Here is a set of 6 numbers10 3 11 8 15 13
4
To find the mean we add the numbers and divide by
6.
10
3
11
8
15
13






60
The mean is 10
?
60
6

10
5
Notice that if we add 5 to each number 10 3
11 8 15 13 5 become15 8 16 13 20 18
6
The mean of the new numbers increases by 5.
15
8
16
13
20
18






90
The mean is 15
?
15
90
6

7
Unlike the median the mean is influenced by
extreme values.
10
3
11
8
15
13
8
If we replace 13 by 613.
13
10
3
11
8
15
613
The mean becomes 110.