  Position probability distribution of a set of massive mutually exclusive
particles in one dimension has been defined. Examples with a given two mutually
exclusive particles system are considered. It is emphasized that quantum
particles at finite potentials can not be regarded as a mutually exclusive
system or they are indistinguishable. Afterward, it is attempted to ascribe a
mutually exclusive system to continuous mass densities of a rigid body to
calculate average values. We do this by applying correspondence principle with
regard to probability densities.
