This paper demonstrates an approach to investment decisions using an exact scientific method, which includes ranking investment projects according to their financial and market efficiency grades. Static and dynamic grading methods, as well as multi-criterial analysis methods will be used for this purpose. During the process of solving investment-related decision problems, eighteen particular investment projects were used and seven methods of multi-criterial analyses were implemented in order to form a ranking list regarding the investment projects and selecting the most reasonable project. In order to form the ranking list of the projects, a comparison between the multi-criterial analysis methods has been made and the most reasonable method for investment-related decision making has been choosen.