Highlight the statements that indicate an informal tone.

1. Yo, what's up?
2. Greetings, ladies and gentlemen.
3. Pardon me, is this the correct address?
4. I'm totally going to lose my mind right now.
5. Our prospects remain sound, provided that we steer clear of improper investments.
6. I had a chance, but I blew it.
7. Your library book is overdue.