Solving parametric linear systems, involving uncertainties in the parameters, is an important part of the solution to many scientific and engineering problems. Usually, in most engineering design problems, models in operational research, linear prediction problems, etc. there are complicated dependencies between coefficients. The main reason for this dependency is that the errors in several different coefficients may be caused by the same factor. For this reason, the interval analysis will be the tool which we will use for solving this type of problems. Interval methods (validated methods) not only can determine such guaranteed error bounds on the true solution, but can also verify that a unique solution to the problem exists.