Volume 1. Basic Concepts of Probability Theory and Mathematical Statistics . Volume 2. Markov chains as a starting point of the theory of random processes and their applications Volume 3. Information and coding theory. Volume 1. Basic concepts of probability theory and mathematical statistics - To master probability theory and mathematical statistics, training in solving problems and developing intuition is no less important , than the study of proofs of theorems a wide variety of problems in this subject makes it difficult for students to transition from lectures to exam problems , From them, to practice.... In view of , that the subject matter of this book is critically important for modern applications as well (financial mathematics, Management, Telecommunications , Signal Processing , Bioinformatics , as well as for applications of classical (actuarial mathematics, Sociology , Engineering , The authors have collected a large number of exercises , Complete Solutions . These solutions are adapted to the needs and skills of students. For the convenience of learning the text, the authors cite a number of basic mathematical facts in the book, in addition, the text is provided with historical deviations. Volume 2. Markov chains as a starting point of the theory of random processes and their applications - To master probability theory and mathematical statistics, training in solving problems and developing intuition is no less important than the study of proofs of theorems a wide variety of problems in this subject makes it difficult for students to transition from lectures to exam problems , From them to practice. The specific subject matter of this volume, the Markov chain and their applications, has been experiencing a great upsurge in recent times. Many remarkable theoretical results have been obtained in this field, which for a long time was considered by many experts as a dead zone. It is the applied research that plays an active role in the development of this field. The subject of this book is critically important for both modern applications (financial mathematics, management, telecommunications, signal processing, bioinformatics) and classical applications (actuary mathematics, sociology, engineering). The authors collected a large number of exercises equipped with complete solutions. These solutions are adapted to the needs and skills of students. The necessary theoretical information is given in the course of the presentation, in addition, the text is provided with historical deviations. Volume 3. Information Theory and Coding - For mastering such sections of applied mathematics, Theory of Probability , Mathematical statistics, Information Theory and Coding , training in solving problems and developing intuition are not less important , than the study of proofs of theorems a wide variety of problems in this subject makes it difficult for students to transition from lectures to exam problems , From them, to practice........................................ This volume includes a standard package of information and theoretical material, usually read in the faculties of computer science and electronics, as well as applied mathematics of leading universities. This describes both probabilistic and algebraic aspects of information theory and coding, including both the foundations of the theory and some of its modern aspects. The subject of this book is critically important for modern applications (telecommunications, signal processing, computer science, cryptography). The authors collected a large number of exercises equipped with complete solutions. These solutions are adapted to the needs and skills of students. The necessary theoretical information is given in the course of the presentation, in addition, the text is provided with historical deviations.