There is a ratio of 5 boys to 3 girls in the chorus. they are 24 boys in the chorus. how many girls are there?

Ok, so at first this question seems tricky, since 5 does not go into 25.  However, you can't have a percentage of 1 person.  Since 5 goes into 25 5 times, then we will go with that.  So multiply 3 x 5 to get 15 girls.  Because you can't have a fraction of a single person.

You have to use proportion for this problem, so you do 
 
5 boys  =  3 girls
24 boys =  ? girls
24 times 3 equals 72. 72 divided by 5 equals 14.4. You have to round this answer to get 15 girls.
Hope this helped :D