In teaching of the probability, teachers focus on the choice and solving problems related to everyday life. In this paper, we analyze the solutions of tasks with similar focus. These tasks were given to students as answer sheets. The aim was to explore the approaches of high school students to the solutions of probability tasks and identify the most common mistakes. In the introduction of paper, we highlight the important position of probability theory in the State educational program. The main part describes the aims, methods and organization of the research.We focus on the selected topics of probability and analyze solutions of several tasks. In conclusion, we summarize the partial findings. We also reflect how to eliminate shortcomings in the knowledge of students in teaching of the probability.