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At Annville Junior High School, 30% of the students in the Math Club are in the Science Club, and 80% of the students in the Science Club are in the Math Club. There are 15 students in the Science Club. How many students are in the Math Club?

Mr.Owl  Oct 21, 2017
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6+0 Answers

 #1
avatar+5241 
+2

There are  15  people in the science club.

 

80% of the people in the science club are in both the science and math clubs, so...

 

number of people in both clubs  =  0.8 * 15  =  12

 

Let the number of people in math club  =  m

 

30% of the people in the math club are in both the science and math clubs,

and remember there are  12  people that are in both clubs, so...

 

0.3m  =  12

 

m  =  12 / 0.3

 

m  =  40

hectictar  Oct 21, 2017
 #2
avatar+78632 
+3

There are 15 students in the Science Club.......80%  of these are in the Math Club....

 

Note that 80%  =  4/5....so 4/5 * 15  =  60/ 5 = 12 

 

So....12 students in the Science Club are Math Club members

 

And these 12 represent 30% of the Math Club

 

Call the total members in the Math Club, M

 

So.....

 

30% of M  = 12      or, put another way

 

.30 M  = 12        divide both sides by .30

 

M  =  12 / .30  =  40 students in the Math Club

 

 

 

cool cool cool

CPhill  Oct 21, 2017
 #3
avatar+78632 
+1

Sorry, hectictar.....I didn't see that you were answering, too....smiley smiley smiley

 

 

 

cool cool cool

CPhill  Oct 21, 2017
 #4
avatar+5241 
+1

I went into hiding!!  smiley

 

Well..... I logged out before I started answering because I didn't know for sure if I could get it   smiley

hectictar  Oct 21, 2017
 #5
avatar+78632 
+1

Aha....a "stealth" answerer...........the sneakiest kind.....LOL!!!

 

 

cool cool cool

CPhill  Oct 21, 2017
 #6
avatar+5241 
+1

They'll sneak up right behind you...and suddenly....BOO!!

 

 

It  is close to Halloween, after all !!! Gotta watch out!!  laughlaugh

hectictar  Oct 21, 2017
edited by hectictar  Oct 21, 2017

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