Anna L.

asked • 06/21/15

If sets G & H are defined below, the # of girls at JJHS is 230, & there are 200 taking history class at JJHS, how many girls are taking history class?

Set G: set of all girls attending Johnson Junior High School
Set H: set of all students taking a history class at Johnson Junior High School
 
thank you so much!!

Gregg O.

Is 200 the number of total students (girls and boys) taking history, or the number of girls taking history?  Also, there needs to be more information given to solve the problem.
 
We are looking for a set whose members are girls AND history students, which is clue that it's the intersection of sets G and H.  If we were to draw a circle for set G, and then another one which overlaps it for set H, the intersection would be the region of overlap.
 
Assuming 200 is the total number of students in the history class, here's how we can approach the solution.  Let's make some new sets:
 
Set I (girls not in history class) = the part of Set G not in the overlap with Set H
Set J (male students in history class) = the part of Set H not in the overlap with Set G
Set K (girls who are in history class) = the overlap (intersection) of sets G and H
 
We know that (# of girls in history class) + (number of girls not in history class) = (total number of girls at JJHS)
                            elements of I            +       elements of K                           = 230.
 
And, assuming there are 200 students total in the history class,
(# of girl history students ) + (# of male history students) = (total number of history students)
             elements of K       +        elements of J               = 200.
 
That would be how to set up the problem, but need more info to answer it!
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06/22/15

Anna L.

Thank you so much for the help!!
Report

06/22/15

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