by tommywallach Tue Dec 24, 2013 5:53 pm
Hey Yellowpad,
Consider this equation:
Total People = V + M + B - (# of people in exactly 2 groups) - 2 * (# of people in all 3 groups) + No group people (question says there aren't any of these, because everyone takes a sport)
Does this make sense? Anyone in 2 groups has been counted twice, and anyone in all 3 groups has been counted three times, so we have to toss out those duplicates.
25 = 15 + 12 + 8 - (2 group people) - 2 * (3 group people) + 0
25 = 35 - 2 group people - 2 * (3 group people)
So how many people can take all three? Well, if we assume NO ONE is in just 2 groups, then all of our overlap could be attributed to people in all 3 groups.
25 = 35 - 0 - 2 * (3 group people)
0 = 10 - 2 * (3 group people)
2 * (3 group people) = 10
3 group people = 5
The answer is 5. I don't know where your solution came from. : )
(feel free to ask follow-ups...I know this can be confusing)
-t