ABSTRACT
The statistical term used for ‘average’ is the arithmetic mean or just the mean. Other measures of central tendency may be used and these include the median and the modal values.
The arithmetic mean value is found by adding together the values of the members of a set and dividing by the number of members in the set. Thus, the mean of the set of numbers: f4, 5, 6, 9g is:
4 C 5 C 6 C 9 4
, i.e. 6
In general, the mean of the set: fx1, x2, x3, . . . , xng is
x D x1 C x2 C x3 C Ð Ð Ð C xn n
,written as ∑ x
n
where ∑
is the Greek letter ‘sigma’ and means ‘the sum of’, and x (called x-bar) is used to signify a mean value.
