Assuming the chances are purely random (which they are not) your approach is correct. If you were talking about picking colored marbles I'd say that's a sound approach, however be warned that applying for and obtaining a job has little to do with chance and everything to do with perception. If you (and I'm not saying you cridex) smell offensively bad then the probability of you getting a job is effectively 0. There is a volume of research on this topic but that depends on how interested you are in this.