This interview question can come in many flavors: What do you want to do with your life? What are your goals? What is your dream job? What do you want to do with your college degree?
However your interviewer phrases the question, the goal is similar. The college admissions folks want to see if you have thought about your future. A lot of students don't succeed in college for the simple reason that they don't have a clear sense of why college is important to them and their goals. This interview question is subtly asking you to show how college fits into your long-term planning.
Realize that you definitely do not need to know what you want to be doing ten years from now. College is a time of exploration and discovery. Many prospective college students have not yet been introduced to the fields that will define their future careers. The majority of students will change majors before they graduate. Many students will have careers that aren't directly connected to their undergraduate majors.
That said, you don't want to evade the question. Answers such as these may be accurate, but they won't impress anybody: * "I don't know." True enough, but keep on reading to see a better way to present your uncertainty. * "I'm not sure what I'll be doing, but I want to be making lots of money." This answer suggests that you have no academic interests, but you have strong materialistic desires. Such attitudes aren't very attractive to a college that is trying to enroll an interesting and engaged group of students. * "I want to be working for a big company." Try to focus more. What type of company? Why? A vague answer isn't going to create a strong impression. * "I hope I'll be married with kids." That's fine, but the interviewer isn't really asking about your personal life (in fact, it wouldn't be appropriate for an interviewer to ask about your future plans for family and marriage). Keep focused on career goals