  In this paper we discuss an empirical phenomena known as the 20-60-20 rule.
It says that if we split the population into three groups, according to some
arbitrary benchmark criterion, then this particular ratio implies some sort of
balance. From practical point of view, this feature often leads to efficient
management or control. We provide a mathematical illustration, justifying the
occurrence of this rule in many real world situations. We show that for any
population, which could be described using multivariate normal vector, this
fixed ratio leads to a global equilibrium state, when dispersion and linear
dependance measurement is considered.
