You can determine your answer for this question by listing all the possible orders that the students may be seated. Let's say that the finalists names are: A, B, C, and D. They can be in the following orders:
You can also determine your answer in a simpler manner by using the fundamental counting principle:
There are 4 different possible students that can sit in the first seat. After that student sits down, there are 3 choices for the second seat. When that student sits there are 2 choices for the third seat and then finally only 1 person that can sit in the last seat. This can be modeled by:
4 x 3 x 2 x 1 = 24 different ways that they may be arranged on stage!