Question 1164746
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If 3 play all three sports, and 10 play both football and soccer, the 7 (10 minus the 3 that do all three) play ONLY F and S.  Likewise, 5 play both S and B, so 5 minus 3 = 2 play ONLY S and B.  And then 9 minus 3 is 6 play only F and B.  The 7 that play ONLY F and S, the 3 that play all three, and the 6 that play only F and B add up to 16 that play F and something else, so 19 minus 16 leaves 3 that play F ONLY.  Likewise, 5 play S ONLY.  Summary:


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F only         3
S only         5
F and S only   7
F and B only   6
S and B only   2
All three      3
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These add up to 26.  Since all 30 boys did something...


You can figure the rest.
																
John
*[tex \LARGE e^{i\pi}\ +\ 1\ =\ 0]
My calculator said it, I believe it, that settles it
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