Final answer:
You would use 'tu' for your little brother and the 4-year-old girl you babysit. You would use 'vous' for your piano teacher, three friends in the hallway, the school principal, the boy in your history class, and your new neighbors.
Step-by-step explanation:
1. You would use 'tu' to speak to your little brother.
2. You would use 'vous' to speak to your piano teacher.
3. You would use 'vous' to speak to three friends you see in the hallway.
4. You would use 'vous' to speak to the school principal, Madame Simon.
5. You would use 'vous' to speak to the boy in your history class.
6. You would use 'tu' to speak to the 4-year-old girl that you babysit.
7. You would use 'vous' to speak to your new neighbors M. and Mme Rousseau.
Learn more about Use of 'tu' and 'vous' in French