According to the study of
statistics a random variable is one which can have any of a particular range of values, but does not have an equal probability of having each of those values. For example, the mark of a first year
statistics student could be anything from 0-100% but it is most probable they will have a mark within two
standard deviations of the
median mark for the class.
The roll of a dice does not represent a random variable since there is an equal probability that it will land on any side.
Statistics that are random variables are often expressed on a
histogram.