Hi, I am a 2nd year student in Economics. I have some difficulties with probability. Here is a problem that I cannot solve and I need some help. It is supposed that only 50% of the students of a sample will go up to the level master. One chooses by chance 18 students. Which is the probability so that at least 10 go up to the level master. I want just to know in this exercise, which is the law of probability that one must apply. Thank you for your assistance, and I'm so sorry for my bad English.