Problem concerns the distribution of mandates in collegial bodies of communities of states. The number of delegates representing each member of community depends on the number of its population. The paper analyzes the fairness of different kinds of relationship involving the number of representatives in collegial bodies of communities of states, in search of the fairest relationship. The research aims at comparing different ideas of how the numbers of representatives are determined reflecting the population of member states. Literature review, elementary probabilistic tools and mathematical analysis of degressive proportionality are employed. The main result of the paper demonstrates that the two fundamentally different approaches to the problem of distribution of mandates in collegial bodies may lead to similar solutions. A probabilistic approach (based on the voting power) and the concept of degressive proportionality (without additional assumptions) do not exclude each other, but, quite the contrary, may complement each other. The Penrose law and the rule of degressive proportionality, when suitably interpreted, are two sides of the coin. Degressive proportionality, as written in the Lisbon Treaty, is a vague idea.