1) D
2) Unsure
3) D
4) Unsure
5) A(?)
6) A
7) Unsure
8) C
9) Unsure
10) D
Sorry for the ones I was unable to help with, but I figured I'd give you the answers to the ones I know at least.
It would be 2.5% because you would set it up as 0.5=p x 20 you divide each side by 20 which should equal 0.025. you move the decimal two places to the right so p actually equals 2.5%