SOLUTION: At an after school event, 5/9 of the students were 8th graders and the rest were 7th graders. Of the students who were in 7th grade, the ratio of boys to girls is 3:5. What percent

Question 1108740: At an after school event, 5/9 of the students were 8th graders and the rest were 7th graders. Of the students who were in 7th grade, the ratio of boys to girls is 3:5. What percent of ALL students at the after school event were boys who are in the 7th grade?
Answer by ikleyn(52803) (Show Source): You can put this solution on YOUR website!
.

Let x = the number of the boys who were in 7th grade.


Let Z = the number of ALL students.


They want you determine the ratio x/Z  (it is almost the same as percentage).



    Let Y be the number of all 7th grade students.  


    Notice that  = , as it follows from the condition.


    Also from the condition  =  = .



Now we have EVERYTHING to calculate 


     =  =  =  = .


Thus we just found the ratio   = .


Hence, the percentage under the question is   =  = 16.667 %  (approximately).

* * * Solved. * * *

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