Motivational characteristics of learners have shown to be more predictive for proficiency when they are measured for a specific content domain. For proficiency in the area of probability and statistics, there is still a need for research on the role of motivational variables. In particular, taskspecific motivation and interest might contribute to our understanding of the impact of motivational dispositions on the use of learning opportunities. Accordingly, this paper presents empirical results in this area, which are part of the research project RIKO-STAT. We concentrate on the data of 350 prospective teachers, who were asked about content domain-specific and taskspecific motivation and self-efficacy and about solutions to given tasks which were parallelised with the motivation questionnaire. The results suggest interdependencies between task-specific motivation and the proficiency of solving the tasks.