The Sabine and Eyring equations for predicting the reverberation time are widely used in room acoustic design practice, often extending to spaces in which their applicability assumptions are not met. In this paper we test these widely used statistical equations along with the methods and applicability criteria of the European standard EN 12354-6:2003 on data set of more than 10,000 different rectangular room models and propose the application of new classification methods where the Sabine and Eyring equations can be used. Classification is performed in comparison with reverberation times predicted by numerical room acoustic simulations. We present the implementation of the method in the soundy.ai application.