How did career assessment test/ placement test help you decide on your major?

Hi again...great questions, I used a lot of career assessments when I was younger and even now. There are many good ones out there, may I suggest the MBTI, Myers Briggs Type Indicator sometimes called Kiersey Temperment Sorter and other names. It basically gives you a 4 letter code that can help you understand your personality and help with career choices, relationships, etc....Introvert vs Extrovert, Sensing vs Intuitive, Feeling vs Thinking and Judging vs Perceiving. There are free online versions of this and you can buy books on it too.
Good luck!

Good question and one that needs to be asked. The career placement test is not a know all, end all assessment. It just gives you some ideas about what you like to do so you can make the initial decisions. You are always in charge of your career and have the ability at any time to change your mind. Use the tool to get ideas to get you started. Once you start in College, you don't have to stick with your initial decisions. Use the first year to take the general requirements and talk to the other students and professors in the suggested area you are looking at. Use this knowledge to assist in making a final decision.
Once you get your degree, it still doesn't mean you are stuck in that particular career. Leverage the fact that you had the fortitude and willingness to pursue a degree (in whatever subject) do demonstrate your commitment and dedication to a goal. This is often more important to hiring managers than what the subject matter was.
Personally, I started my College experience as a Physics major, changed to a Chemistry major, a General Science major and then got my degree in Animal Science. I started in the meat industry using my degree and then leveraged it so I am currently in the high tech industry. Nothing is set in stone so be open to opportunities as they present themselves. Build a network as you go and don't limit yourself to what a single test implies. There are multiple tools available to assist you in making an informed decision about your likes and dislikes, so don't get caught in the trap of thinking the results of one test is the end all of the decision process. Your likes and dislikes will change over time as you gain more experience so be open to change.
Hope this helps. Good luck!