Posted by Jen on Thursday, July 7, 2011 at 11:40pm.
The National Association for Women in Science asked recent high school grads if they had taken certain science classes. Of those surveyed, 23 said they had taken physics, 47 said they had taken chemistry and 5 said they had taken both. Seven said they had taken neither. How many recent high school grads were surveyed?

MATH  Reiny, Friday, July 8, 2011 at 12:19am
use Venn diagrams.
draw two intersecting circles, label one P , the other C
place 5 in the intersection of the two circles
place 18 in the P circle outside the intersection, (notice you have a total of 23 in P)
place 42 in the C circle outside the intersection,
(notice you have a total of 47 in C)
add them up: 18+5+42 = 65
or
N(P OR C) = N(P) + N(C)  N(P AND C)
= 23+475
= 65 
MATH  Jen, Friday, July 8, 2011 at 12:23am
hmmmmmm im kind of getting it.....but for some reason when i did it my answer was 72....geometry is not my best subject haha

MATH  Ron, Friday, July 8, 2011 at 5:22am
72 is right. Reiny forgot to add 7 who said they had taken neither.
65 + 7 = 72 
MATH  Anonymous, Wednesday, April 13, 2016 at 12:51pm
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