answer:That example is indeed tough. At first glance you’re not certain if the chronology of the meetings matters, or you’re just determining which ten students get to have meetings. But you’re absolutely right; since the question mentions meetings happening one at a time, chronology comes into play. Here are two very similar questions, but it will be clear which one is a combination and which is a permutation: There were ten questions on last night’s homework assignment, and the teacher wants ten students to write the answers up on the board. If there are twenty students in the class, and no one student may do two questions, in how many ways can the students put the homework assignment on the board? There were ten questions on last night’s homework assignment, and the teacher wants ten students to write the answers up on the board. If there are twenty students in the class, and no one student may do two questions, how many different groups of students can participate? The difference is subtle, but the first is a permutation and the second a combination. The first specifies a difference between Mike doing problem #1 and Mike doing problem #9: if Mike does a different problem, that’s a different “way” in which the problems can be written on the board. The second only asks about the group of students participating versus the group of students not participating; it doesn’t matter which problem each student does. Combinations generally focus on choosing a group, permutations focus on choosing a lineup.