This paper analyzes the treatment of the random variable and its applications on probability distributions in Chilean high school textbooks, from the Ontosemiotic Approach to Mathematical Knowledge and Instruction. Thus, a model is used for the analysis of mathematical objects in the Chilean textbooks and the Chilean school curriculum by means of content analysis. The results show a diversity of languages, concepts, propositions, procedures and arguments linked to the topics, although some of them are identified in the curriculum and excluded in books or inversely, showing a lack of coherence between the documents. [ABSTRACT FROM AUTHOR]