Solution: 1) According to the meaning of the question, girls 1/2+65438 boys +0/3+65438 boys +0/3+65438 girls +0/2 = 13+ 12.

=> (boys+girls) 5/6 = 25 = > Boys+girls =30, that is, there are 30 people in the choir.

2) It is known that boys 1/2, girls 1/2= 15, boys 1/2, girls 1/3= 12.

So there are more girls 1/2 than girls 1/3, 15- 12=3.

So the number of girls is 3/(1/2-1/3) =18.