1. The problem statement, all variables and given/known data Three children, each accompanied by a guardian, seek admission in a school. The principal wants to interview all the 6 persons one after the other subject to the condition that no child is interviewed before its guardian. In how many ways can this be done ? 2. Relevant equations 3. The attempt at a solution So, I read the solution to this problem, because I could only work it out with a lot of casework (I did get the right answer), but this question wasn't supposed to be that time consuming. So, here's what I read-- No. of ways = 6C2 * 4C2 * 2C2 = 90 That doesn't make much sense to me. Help?