I need tha answers that 1, 2, 3, and 4 is permutation or combinations and why?

3.6 Exercise Set In Exercises 1-4, does the problem involve permutations or combinations? Explain your answer. 1. An online test program has a bank or 30 questions for a particular test. If an instructor wants to pick 10 questions from the bank of 30 questions, in how many ways can the test be made? 2. A contest has three prizes, a car, a boat, and a side-by-side. If there are 25 contestants how many ways can the prizes be awarded? 3. A secret code to open a door consist of 5 letters that can not repeat. How many different 5 letter codes are there? 4. A contestant on a game show is shown 10 doors. The contestant gets to pick 3 doors and gets to keep the prize behind each door. How many different ways can the contestant pick the three doors