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?

Answer 1

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+47-5
= 65

Answer 2

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

Answer 3

72 is right. Reiny forgot to add 7 who said they had taken neither.

65 + 7 = 72