The percent student failures in the physics 1 class of Universidad de los Andes, since the first semester of 2001 though the first semester of 2005, is about 45%. To be able to detect and diagnose the basic deficiencies of the students entering to the first course of physics, we have designed a quiz that has to be answered by the new students in the first week of classes. With this quiz we have been able to obtain information about the basic deficiencies that the students have in arithmetic, algebra, geometry, trigonometry and basic physics. The results of this quiz have been correlated with the final grade of physics 1, results of the ICFES exam, and other results which enable us to predict the probability that the students have to pass the physics 1 course in Universidad de los Andes and suggest to take the course of PREPHYSICS to the students with low probability of success, other statistical analysis that are presented here give information about the average academic level of calendar A students compared to calendar B students. [ABSTRACT FROM AUTHOR]